Solution Found!
Answer: A large boulder is ejected vertically upward from
Chapter 2, Problem 48E(choose chapter or problem)
A large boulder is ejected vertically upward from a volcano with an initial speed of 40.0 m/s. Air resistance may be ignored. (a) At what time after being ejected is the boulder moving at 20.0 m/s upward? (b) At what time is it moving at 20.0 m/s downward? (c) When is the displacement of the boulder from its initial position zero? (d) When is the velocity of the boulder zero? (e) What are the magnitude and direction of the acceleration while the boulder is (i) moving upward? (ii) Moving downward? (iii) At the highest point? (f ) Sketch \(a_{y}-t\), \(v_{y}-t\) and y-t graphs for the motion.
Questions & Answers
QUESTION:
A large boulder is ejected vertically upward from a volcano with an initial speed of 40.0 m/s. Air resistance may be ignored. (a) At what time after being ejected is the boulder moving at 20.0 m/s upward? (b) At what time is it moving at 20.0 m/s downward? (c) When is the displacement of the boulder from its initial position zero? (d) When is the velocity of the boulder zero? (e) What are the magnitude and direction of the acceleration while the boulder is (i) moving upward? (ii) Moving downward? (iii) At the highest point? (f ) Sketch \(a_{y}-t\), \(v_{y}-t\) and y-t graphs for the motion.
ANSWER:Solution 48 E
Step 1 :
Considering the data given
Initial velocity of the boulder
We need to find the time by the boulder to move upward
Final velocity
The acceleration acting upon the boulder is given by gravitational force
Hence we have
Since the boulder is moving against gravitational force
Thus we get