Study Guide Physics 1 - Exam 1 – Feb. 8, 2017
Test will cover Lessons 1-4 + a question from the lab activities: Cars or Freefall and a long answer question from: Freefall and 1D kinematics.
1) S.I. Units and conversions
2.6 Ms = 2.6 X 106 s
12 km = 12000 m
1.7 cm = 0.017 M
3.5 mg = 0.0035 g
0.7 µM = 7.3 X 10 -7 M
55.01 ns = 5.501 X 10-8s
1.06 ps = 1.06 X 10-12 s
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1 inch = 2.54 cm
1 M = 1 Yard
2 km = 1 Mile
1 thumb width = 2 cm
1 mm = 1 cubic cm
1 mL = 1 cm3
Unit conversion example:
Convert 1 m2to cm2 1 m2/1 * (100 cm/1m) * (100 cm/1 m) = 10 000 cm2Don't forget about the age old question of Which type of law involves disputes between private individuals or groups?
2) When solving problems:
Diagram with +x or +y direction and origin (or -)
List all 6 quantities and the values (unknown and known)
Show the physics!!
Write down the full equation you intend to use in its original form. Solve the problem and box your final answer. Round answers to 2 decimal places.
∙ The description of motion.
∙ Scalar quantity
∙ Ex: 30 miles
∙ Only a number, with or without units. We also discuss several other topics like Is trade off and opportunity cost the same?
∙ Ex: 30 m/s
∙ Requires magnitude and direction.
Average speed = total distance / total time = Distance /change in time
Average velocity = total displacement / total time elapsed = r (distance) / change in time We also discuss several other topics like How to get to peace?
Displacement = How far is it from its original position. It may have travelled a total of 100 miles, but if it moved 80 miles forward and 20 miles back, the displacement is 60 miles.
Average x-component of velocity = change in x / change in t = change in x position / change in time.
∙ Change in time = time final – time initial
∙ Ex: time1 = Distance 1 / Velocity 1 average = mi / (mi/hr) = # hours
∙ Distance / time = miles/hour
∙ Velocity = How fast and in what direction. How far did you get in a given direction and how long did it take you to get there? If you get nowhere and go fast, your x component of velocity is still 0.
∙ Slope of a graph using a given position and time gives velocity. If you want to learn more check out Why is genetic variation in a population necessary for evolution?
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∙ If velocity is 0, the object is not moving.
4) Y = mx+b
Slope = rise/run
Get your slope from your graph in Excel by using a best fit line on your data and displaying the equation on your chart. Slope remains the same regardless of systematic error.
5) Uncertainty = Error Analysis
F. U. (t) = ��(��)
The fractional uncertainty of anything is calculated in this manner. The example above is calculating the fractional uncertainty of time. Uncertainty of time divided by time. You must first find your uncertainty in your measurement by deciding what the closest you can read that measurement to, the amount of error in your measurement. When reading a meter stick, that might be 0.2 cm or 0.1 cm. You must calculate your fractional uncertainty for each measurement graphed, seconds and cm for example. Use the biggest uncertainty calculated. Round to 1 significant figure.
6) Know how to calculate Area.
∙ Area = L*W = M2
Area of a rectangle.
∙ �� = ������
Area of a circle
7) Acceleration and 1D Kinematics
∙ Acceleration = the change in velocity over time
∙ Average acceleration = the change in velocity over the change in time ∙ (m/s) / s = m/s2
∙ X component of acceleration = change in velocity at x point / change in time ∙ Gives the slope Ex: Change in y / change in x
∙ If acceleration is 0, there is no slope.
∙ If the acceleration is going in the same direction as the +x direction, acceleration is positive.
∙ If acceleration is going in the opposite direction of +x or the -x direction, then acceleration is negative.
X final = X initial + Velocity initial x * time + ½ acceleration x *time2
∙ Missing velocity final x
X final = X initial + ½ (Velocity initial x + Velocity final x) time
∙ Missing acceleration x
Velocity final x = Velocity initial x + acceleration x * time
∙ Missing x final
Velocity final x2 = Velocity initial x2 + 2 * acceleration x (x final – x initial)
∙ Missing time
If there is only one quantity unknown, choose an equation with that quantity in it and solve using algebra.
If there is another quantity missing, choose the equation with that quantity missing and solve for your desired quantity.
∙ Always points at the center of the earth
∙ If the only force acting on an object is gravity, it is in freefall
∙ Acceleration due to gravity = g = 9.8 M/s2 = 32 ft./s2
∙ Acceleration due to gravity is a magnitude of the vector and is always positive. This is a constant acceleration.
∙ Only direction changes