Problem 2RCQ

In the question 1, is your approximate speed relative to the Sun as you walk down the aisle of the train slightly more or very much more?

Question 1

If you walk at 1 km/h down the aisle of a train that moves at 60 km/h, what is your speed relative to the ground?

3/11/2016 Ch 08 HW Ch 08 HW Due: 11:59pm on Friday, March 11, 2016 To understand how points are awarded, read the Grading Policy for this assignment. Problem 8.2 A 400g model rocket is on a cart that is rolling to the right at m/sp . The rocket engine, when it is fired, exerts a 9N0 vertical thrust on the rocket. Your goal is to have the rocket pass through a small horizontal hoop that is 20m above the launch point. Part A At what horizontal distance left of the loop should you launch Express your answer to two significant figures and include the appropriate units. ANSWER: x = 6.2m Correct A Mass on a Turntable: Conceptual A small metal cylinder rests on a circular turntable that is rotating at a constant rate, as illustrated in the diagram. Part A Which of the following sets of vectors best describes the velocity, acceleration, and net force acting on the cylinder at the point indicated in the diagram https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 1/25 3/11/2016 Ch 08 HW Hint 1. The direction of acceleration can be determined from Newton's second law According to Newton's second law, the acceleration of an object has the same direction as the net force acting on that object. ANSWER: a b c d e Correct Part B LetR be the distance between the cylinder and the center of the turntable. Now assume that the cylinder is moved to a new locatiR/2 from the center of the turntable. Which of the following statements accurately describe the motion of the cylinder at the new location Check all that apply. Hint 1. Find the speed of the cylinder Find the speedv of the cylinder at the new location. Assume that the cylinder makes one complete turn in a period of timT. Express your answer in terms of R andT . ANSWER: https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 2/25 3/11/2016 Ch 08 HW πR v = T Hint 2. Find the acceleration of the cylinder Find the magnitude of the accelerata of the cylinder at the new location. Assume that the cylinder makes one complete turn in a period of Ti.e Express your answer in terms of R andT . Hint 1. Centripetal acceleration Recall that the acceleration of an object that moves in a circular patr with constant speed v has magnitude given by v2 a= r . Note that both the velocity and radius of the trajectory change when the cylinder is moved. ANSWER: 2 a = 2π R T 2 ANSWER: The speed of the cylinder has decreased. The speed of the cylinder has increased. The magnitude of the acceleration of the cylinder has decreased. The magnitude of the acceleration of the cylinder has increased. The speed and the acceleration of the cylinder have not changed. Correct Conical Pendulum I A bob of massm is suspended from a fixed point with a massless string ofLl (i.e., it is a pendulum). You are to investigate the motion in which the string moves in a cone with haθ.angle https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 3/25 3/11/2016 Ch 08 HW Part A What tangential speed,v, must the bob have so that it moves in a horizontal circle with the string always making an angleθ from the vertical Express your answer in terms of some or all of the variablesm ,L, and θ, as well as the acceleration due to gravityg . Hint 1. What's happening here In this situation, which of the following statements is true ANSWER: The bob has no acceleration since its velocity is constant. The tension in the string is less mga. A component of the tension causes acceleration of the bob. Ifθ = 0 the tension in the string would be greater mgan. Hint 2. Find the vertical acceleration of the bob What is averticalthe vertical component of the acceleration of the bob ANSWER: avertical= 0 Hint 3. Find the tension in the string Find the magnitude,T , of the tension force in the string. Express your answer in terms of some or all of the variables m ,L , andθ, as well as the acceleration due to gravityg . https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 4/25 3/11/2016 Ch 08 HW Hint 1. What approach to use You know the vertical acceleration of the bob, and so you know the net vertical force. The force due to the string has both vertical and horizontal components, and so breaking this force into components should allow you to find the magnitude of the tension force, T.ich is ANSWER: mg T = cos θ) Hint 4. Find the horizontal acceleration of the bob Find a general expression ao, the magnitude of the bob's centripetal acceleration, as a function of the tangential speev of the bob. Express your answer in terms ofv and some or all of the variablms,L , andθ. Hint 1. Find the radius of the bob's motion The bob moves uniformly in a circle of what rrius Express your answer in terms of some or all of the variablms,L , andθ. ANSWER: r = Lsin(θ) ANSWER: v2 a = Lsin θ) Hint 5. Find the horizontal force Find the magnitudeF r, of the inward radial force on the bob in the horizontal plane. Express your answer in terms of some or all of the variablms,L , andθ, as well as the acceleration due to gravitg . ANSWER: Fr = mgtan(θ) ANSWER: https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 5/25 3/11/2016 Ch 08 HW Lsin θ) v = √ Lcos θ g Correct Part B How long does it take the bob to make one full revolution (one complete trip around the circle) Express your answer in terms of some or all of the variablem , L, and θ, as well as the acceleration due to gravityg. Hint 1. How to approach the problem Since the speed of the bob is constant, this is a relatively simple kinematics problem. You know the speed, which you found in the previous part, and you can calculate the distance traveled in one revolution (i.e., the circumference of the circle). From these two you can calculate the time required to travel that distance. ANSWER: Lsin θ) 2π √ gLtan θ sin θ) Correct ± Mass on Turntable A small metal cylinder rests on a circular turntable that is rotating at a constant speed as illustrated in the diagram . The small metal cylinder has a mass of 0kg0, the coefficient of static friction between the cylinder and the turntable is 0.080, and the cylinder is locatmd from the center of the turntable. Take the 2agnitude of the acceleration due to gravity to be 9.81m/s . https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 6/25 3/11/2016 Ch 08 HW Part A What is the maximum speed vmax that the cylinder can move along its circular path without slipping off the turntable Express your answer numerically in meters per second to two significant figures. Hint 1. Centripetal acceleration If you know a body is in uniform circular motion, you know what its acceleration must be. If a body mf mass is traveling with spev in a circle of radRu, what is the magnituda c of its centripetal acceleration ANSWER: mv 2 R mv R v R 2 v R Hint 2. Determine the force causing acceleration Whenever you see uniform circular motion, there is a real force that causes the associated centripetal acceleration. In this problem, what force causes the centripetal acceleration ANSWER: normal force static friction weight of cylinder a force other than those above Hint 3. Find the maximum possible friction force The magnitude fs of the force due to static friction safs≤ fesmax. What isf max in this problem Express your answer numerically in newtons to three significant figures. ANSWER: fmax = 0.157 N Hint 4. Newton's 2nd law To solve this problem, relate the answers to the previous two hints using Newton's 2nd law: F = ma . https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 7/25 3/11/2016 Ch 08 HW ANSWER: vmax = 0.34 m/s Correct ± Banked Frictionless Curve, and Flat Curve with Friction A car of massM = 1200kg traveling at 60km/hour enters a banked turn covered with ice. The road is banked at an angleθ, and there is no friction between the road and the car's tires as shown ig = 9.80m/s 2 throughout this problem. Part A ∘ What is the radiur of the turn θ = 20.0 (assuming the car continues in uniform circular motion around the turn) Express your answer in meters. Hint 1. How to approach the problem You need to apply Newton's 2nd law to the car. Because you2do not want the car to slip as it goes around the curve, the car needs to have a net acceleration of magnitv /r pointing radially inward (toward the center of the curve). Hint 2. Identify the freebody diagram and coordinate system Which of the following diagrams represents the forces acting on the car and the most appropriate choice of coordinate axes https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 8/25 3/11/2016 Ch 08 HW ANSWER: Figure A Figure B Figure C Hint 3. Calculate the normal force Findn , the magnitude of the normal force between the car and the road. Take the positive x axis to point horizontally toward the center of the curve and the positive y axis to point vertically upward. Express your answer in newtons. Hint 1. Consider the net force The only forces acting on the car are the normal force and gravity. There must be a net acceleration in the horizontal direction, but because the car does not slip, the net acceleration in the vertical direction must be zero. Use this fact tn.find Hint 2. Apply Newton's 2nd law to the car in the y direction Which equation accurately describes the equation for the net force acting on the car in the y direction ANSWER: ∑F =yncosθ+Mg ∑F =ynsinθ+Mg ∑F =yncosθ−Mg ∑F =ynsinθ−Mg ANSWER: https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 9/25 3/11/2016 Ch 08 HW n = 1.25×104 N Hint 4. Determine the acceleration in the horizontal plane Take the y axis to be vertical and let the x axis point horizontally toward the center of the curve. By applying ∑F = xa x in the horizontal direction, deae, the magnitude of the acceleration, using your result for the normal force. Express your answer in meters per second squared. Hint 1. Apply Newton's 2nd law to the car in the x direction Which equation accurately describes the equation for the net force acting on the car in the x direction ANSWER: ∑F = ncosθ x ∑F =xnsinθ ∑F =ncosθ+ Mv 2 x r Mv 2 ∑F =nxosθ− r ANSWER: a = 3.57 m/s 2 ANSWER: r = 77.9 m Correct Part B Now, suppose that the curve is leθ = 0) and that the ice has melted, so that there is a coefficient of static frictioμ between the road and the car's tires as shown in .μmint, the minimum value of the coefficient of static friction between the tires and the road required to prevent the car from slipping Assume that the car's speed is still 6km/hour and that the radius of the curve ms .7.9 Express your answer numerically. https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 10/25 3/11/2016 Ch 08 HW Hint 1. How to approach the problem You need to apply Newton's 2nd law to the car. Because you do not want the car to slip as it goes around the 2 curve, the car needs to have a net acceleration of magnitude v /r pointing radially inward (toward the center of the curve). Hint 2. Identify the correct freebody diagram Which of the following diagrams represents the forces acting on the car as it goes around the curveF fr represents the friction force. ANSWER: Figure A Figure B Figure C Figure D https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 11/25 3/11/2016 Ch 08 HW Hint 3. Calculate the net force What is the net forFenet that acts on the car Express your answer in newtons. Hint 1. How to determine the net force Newton's 2nd law tells you that ∑F = ma ⃗. Because you do not want the car to slip as it goes around the curve, the car needs to have a net acceleration of magnitudv /r pointing radially inward (toward the center of the curve). ANSWER: Fnet = 4280 N Hint 4. Calculate the friction force If the coefficient of friction were μqual, what would beF , the magnitude of the force provided by min fr friction Lmt be the mass of the car ang be the acceleration due to gravity. Hint 1. Equation for the force of friction The force of friction is given by F frμn . Hint 2. Find the normal force What is the normal forcn acting on the car Enter your answer in newtons. Hint 1. Acceleration in the y direction Because the car is neither sinking into the road nor levitating, you can cona y 0 th.t ANSWER: n = 4 N 1.18×10 ANSWER: μ F = min fr Mg F frμ min Mg https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 12/25 3/11/2016 Ch 08 HW ANSWER: μ = 0.364 min Correct Problem 8.6 A 220g block on a 52cm long string swings in a circle on a horizontal, frictionlerpmta .e at 70.0 Part A What is the speed of the block Express your answer with the appropriate units. ANSWER: m 3.81 s Correct Part B What is the tension in the string Express your answer with the appropriate units. ANSWER: 6.15N Correct Problem 8.9 Suppose the moon were held in its orbit not by gravity but by a massless cable attached to the center of the earth. Part A What would be the tension in the cable Use the table of astronomical data inside the back cover of the textbook. Express your answer to three significant figures and include the appropriate units. ANSWER: https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 13/25 3/11/2016 Ch 08 HW T = 2.01×10 N Correct Problem 8.14 The weight of passengers on a roller coaster increases%b as the car goes through a dip withma radius of curvature. Part A What is the car's speed at the bottom of the dip Express your answer to two significant figures and include the appropriate units. ANSWER: v = 14 m s Correct PSS 8.1 CircularMotion Problems Learning Goal: To practice ProblemSolving Strategy 8.1 for circularmotion problems. A cyclist competes in a onelap race around a flat, circular course ofmr . Starting from rest and speeding up at a constant rate throughout the race, the cyclist covers the entire s . The mass of the bicycle (including the rider) iskg . What is the magnitude of the net Force acting on the bicycle as it crosses the finish line net PROBLEMSOLVING STRATEGY 8.1 Circularmotion problems MODEL: Make appropriate simplifying assumptions. VISUALIZE Draw a pictorial representation. Establish a coordinate system with the r axis pointing toward the center of the circle. Show important points in the motion on a sketch. Define symbols, and identify what the problem is trying to find. Identify the forces, and show them on a freebody diagram. SOLVE: Newton's second law is 2 (F net) =∑F =ma =r r mv =mω r 2 , r r (F nett= ∑F = mt t, and https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 14/25 3/11/2016 Ch 08 HW (F net)z= ∑F = 0z . Determine the force components from the freebody diagram. Be careful with signs. Solve for the acceleration, and then use kinematics to find velocities and positions. ASSESS: Check that your result has the correct units, is reasonable, and answers the question. Model The cyclist moves in a circle at an increasing speed. This means that the cyclist has both centripetal and tangential acceleration. Moreover, the rate at which the cyclist's speed is increasing is constant. Thus, to simplify the problem, you can model the bicycle + rider as a particle in nonuniform circular motion and use constantacceleration kinematics to work out your solution. Visualize Part A Which of the following sets of rtz coordinate axes is the most appropriate for this problem The black dot represents the bicycle + rider at an arbitrary instant during the race. ANSWER: Correct Unless otherwise stated, in circularmotion problems always use the usual convention in which the t axis points in the counterclockwise direction. Note that the r axis always points from the position of the cyclist to the center of the course, regardless where the cyclist is along the circular course. This means that the direction of the r axis changes as the cyclist moves. Part B https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 15/25 3/11/2016 Ch 08 HW Identify which of the following forces act on the bicycle + rider system, and sort them accordingly. Drag the appropriate items to their respective bins. ANSWER: Correct Since the motion is horizontal, Newton's second law requires the vertical component of the net force be zero, that is(F net) = ∑F = 0 z . This means that gravity will cancel out the normal force, and we don't need to z worry about these vertical forces. As for the horizontal forces acting on the cyclist, both rolling friction and air resistance oppose the forward motion of the bicycle, so they must act along the tangential direction, opposite to the velocity vector. Static friction, instead, has two effects: It propels the bicycle tires forward (the tires push backward against the earth, and the earth pushes forward on the tires as friction) and prevents the bicycle from sliding sideways. So, it must have both a component along the tangential direction that provides the tangential acceleration and a component along the radial direction that provides the centripetal acceleration. Note that although the effects of rolling friction and air resistance can be ignored, static friction cannot be neglected. If you neglect rolling friction and/or air resistance, you would simply end up with an overestimate of the cyclist's tangential acceleration. If you ignore static friction, instead, you would neglect the only force that provides the cyclist's centripetal acceleration, which is an essential element of circular motion. Part C Below is a top view of the circular course. The black dot represents the bicycle + rider at an arbitrary instant during the race. Assume the bicyclist is traveling around the track in the counterclockwise direction. To simplify the problem, also assume that rolling friction is negligible. (This is reasonable because the contact area between the https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 16/25 3/11/2016 Ch 08 HW bicycle tires and the ground is often very small.) Draw a freebody diagram showing all the horizontal forces acting on the bicycle. Make a reasonable estimation of the direction of each force. Draw the vectors starting at the black dot. The location and orientation of the vectors will be graded. The length of the vectors will not be graded. Hint 1. How to estimate the direction of drag and static friction ⃗ As explained in the previous part, air resistance (drag) opposes the forward motion of the bicycle, so d must act along the tangential direction, opposite to the velocity vector. Static friction, instead, has two effects. It propels the bicycle tires forward (the tires push backward against the earth, and the earth pushes forward on the tires as friction) and prevents the bicycle from sliding sideways. So, f s must have both a component along the tangential direction that provides the tangential acceleration and a component along the radial direction that provides the centripetal acceleration. Since the magnitudes and the exact direction of these forces are unknown, it is sufficient to determine the sign of their components to draw a reasonable freebody diagram. To do that, determine the signs of the components of the net force, which must have the same ⃗ ⃗ signs as the tangential and the centripetal acceleration. Then, draw f s and d so that their vector sum (the net force) has components with the required signs. ANSWER: https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 17/25 3/11/2016 Ch 08 HW All attempts used; correct answer displayed Now, you can complete your pictorial representation. Note that although the tangential acceleration (and therefore the tangential force) is constant through the race, the radiFlr and accelerationar, as well as the angular velocitω, are not constant. So, you should define unique symbols for these quantities at important points in the motion: For this problem, we'll use the subi to refer to valueFi,r,ai,r ωi) at the moment the race begins and the subscripf to refer to valueFf,r,af,r,ω f) at the moment the cyclist crosses the finish line. Keep in mind that you are trying to find the magnitude of the net force at theFff,net line, Your pictorial representation should look like this: Solve Part D Find Ff,net the magnitude of the net force acting on the cyclist at the finish line. Express your answer in newtons to two significant figures. Hint 1. The net force in terms of its components The magnitude of the net force is given by the usual formula for finding the magnitude of a vector in terms of its components: −−−−−−−− 2 −−−− −−−−− 2 Fnet = √ [(Fnet)r] +[(F net t . To find the components of the net force acting on the cyclist at the finish line, use Newton's second law, as explained in the strategy above. That will require you to calculate the components of the cyclist's acceleration at the finish line. Hint 2. Find the tangential acceleration https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 18/25 3/11/2016 Ch 08 HW From the problem introduction, you know that the cyclist speeds up at a constant rate or, in other words, accelerates with constant tangential accelerationa t. Use the appropriate kinematic equation for motion with constant acceleration to findat. Express your answer in meters per second squared to three significant figures. Hint 1. Motion with constant acceleration For a particle in circular motion with constant tangential acceleration, it is convenient to use the equation for the angular displacement θ of the particle in terms of its angular veloωi and angular acceleration α : 2 θ f θ +ωiΔt+ α(it) 1 , 2 where the subscript i refers to initial values at tt = 0, and the subscript f refers to final values at time t = Δt . In this problem, in making one complete circuit of the course, the cyclist's angular position changes by 2π . You also know that the cyclist starts from rest, so her initial angular velocity isω = 0 ( ). i Hint 2. Tangential and angular accelerations Recall that for a particle in circular motion, the relationship between the particle's tangential and angular accelerations, a t and α, respectively, is a t rα , where r is the radius of the circular path. ANSWER: 2 at = 0.489 m/s Hint 3. Find the radial acceleration What is the cyclist's radial acceleration at the finish aine Note that the radial component of the cyclist's f,r acceleration is simply the centripetal acceleration needed to keep the cyclist moving in a circle. Express your answer in meters per second squared to three significant figures. Hint 1. Centripetal acceleration The centripetal acceleration of a particle moving in a circle of radru is v2 ar= r = ω r2 , where v is the particle speed, andω is its angular speed. Therefore, to find the cyclist's centripetal acceleration at the finish lina,f,r you will need to calculate the cyclist's speevf , or, alternatively, the cyclist's angular velocitω,f, at the finish line. In both cases, you will need to know the cyclist's constant tangential acceleration. Hint 2. Find the final angular velocity To find the cyclist's final angular velocωty, you can use the kinematic formula for motion with f https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 19/25 3/11/2016 Ch 08 HW constant angular acceleration : ω f ω +αiΔt) . Considering that the tangential acceleratioat, is related to the angular acceleration by the expression at= rα , wherer is the radius of the circular path, what is the final angular ωef ofty the cyclist Express your answer in radians per second to three significant figures. ANSWER: ωf = 0.209 rad/s ANSWER: 2 a f,r= 6.14 m/s ANSWER: F f,net= 470 N Correct Assess Part E To assess whether your calculations make sense, let's simplify the problem even further and assume air resistance is negligible. In this case, the net force acting on the bicyclist is equivalent to just the force of static friction, and your answer to Part D is the magnitudefs. Based on this value, what is the minimum coefficient of static friμsion between the race track and the bicycle Express your answer numerically to two significant figures. Hint 1. How to approach the problem The magnitude f of the force of static friction is less than or eμ nl, where μ is the coefficient of s s s static friction and is the magnitude of the normal force. Therefore, the minimum coefficient of static friction between the race track and the bicycle can be found by solving the equatiof s μ n s , where you use your result from part D asf . s You made use of the relation (Fnet)z= ∑F = 0 z previously to justify ignoring gravity and the normal force in calculating the net force, because they had to cancel out. Now, use that relation to find the magnitude of the normal force. ANSWER: https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 20/25 3/11/2016 Ch 08 HW μ s = 0.63 Correct This is a reasonable value for the coefficient of static friction. Actual coefficients of static friction between race tracks and bicycle tires usually range from around 0.4 up to 0.7. If you found that your answer implied a coefficient of 1 or greater, then you would know that you had made a mistake. If you found that the minimum coefficient was very small, less than 0.01 for instance, then you might guess that you had made an error as well. Problem 8.20 A toy train rolls around a horizonmadiameter track. The coefficient of rolling friction is 0.15. Part A What is the magnitude of the train's angular acceleration after it is released Express your answer to two significant figures and include the appropriate units. ANSWER: α = 1.6 ra2 s Correct Part B How long does it take the train to stop if it's released with an angularpmp of 35 Express your answer to two significant figures and include the appropriate units. ANSWER: Δt = 2.2s Correct Problem 8.21 A popular pastime is to see who can push an object closest to the edge of a table without its going off. You push the 100 g object and release it m. from the table edge. Unfortunately, you push a little too hard. The object slides across, sails off the edge, fallsm0 to the floor, and lands cm. from the edge of the table. Part A https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 21/25 3/11/2016 Ch 08 HW If the coefficient of kinetic friction is 0.600, what was the object's speed as you released it Express your answer with the appropriate units. ANSWER: m 3.64 s All attempts used; correct answer displayed Problem 8.29 Communications satellites are placed in a circular orbit where they stay directly over a fixed point on the equator as the earth rotates. These are called geosynchronous orbits. The altitude of a geosynchronous orbit is 3.58 ×10 m (≈ 22,000 miles) . Part A What is the period of a satellite in a geosynchronous orbit Express your answer to three significant figures and include the appropriate units. ANSWER: 24.0 hr Correct Part B Find the value gf at this altitude. Express your answer to three significant figures and include the appropriate units. ANSWER: m 0.223 s2 Correct Part C What is the weight of a 2000 kg satellite in a geosynchronous orbit Express your answer as an integer and include the appropriate units. ANSWER: https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 22/25 3/11/2016 Ch 08 HW 0 N All attempts used; correct answer displayed Problem 8.35 You've taken your neighbor's young child to the carnival to ride the rides. She wants to ride The Rocket. Eight rocket shaped cars hang by chains from the outside edge of a large steel disk. A vertical axle through the center of the ride turns the disk, causing the cars to revolve in a circle. You've just finished taking physics, so you decide to figure out the speed of the cars while you wait. You estimate that thm in diameter and the chains ame long. The ride ∘ takes 1s to reach full speed, then the cars swing out until the chains are 30 from vertical. Part A What is the car's speed Express your answer to one significant figure and include the appropriate units. ANSWER: m v = 5 s All attempts used; correct answer displayed Problem 8.43 In an amusement park ride called The Roundup, passengers stand insidema diameter rotating ring. After the ring has acquired sufficient speed, it tilts into a vertical plane, as shown in the figure . Part A https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 23/25 3/11/2016 Ch 08 HW Suppose the ring rotates once every s . If a rider's mass iskg , with how much force does the ring push on her at the top of the ride Express your answer with the appropriate units. ANSWER: 1230 N Correct Part B Suppose the ring rotates once every s . If a rider's mass iskg , with how much force does the ring push on her at the bottom of the ride Express your answer with the appropriate units. ANSWER: 2380 N Correct Part C What is the longest rotation period of the wheel that will prevent the riders from falling off at the top Express your answer with the appropriate units. ANSWER: 6.19 s Correct Problem 8.53 A 200g ball on a 6cm long string is swung in a vertical circle about acmo above the floor. The string suddenly breaks when it is parallel to the ground and the ball is moving upward. The ball reachecma height 600 above the floor. Part A What was the tension in the string an instant before it broke Express your answer to two significant figures and include the appropriate units. ANSWER: https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 24/25 3/11/2016 Ch 08 HW T = 26N Correct Score Summary: Your score on this assignment is 83.6%. You received 125.44 out of a possible total of 150 points. https://session.masteringphysics.com/myct/assignmentPrintViewassignmentID=4099366 25/25