Physics 011
A of PQ#6
Chapter 6: Work and Energy
Practice Questions

Two men, Joel and Jerry, push against a wall. Jerry stops after 10 min, while Joel is able to push for 5 min longer. Compare the work against the wall they each do. 


Joel
does 50% more work than Jerry. 


Jerry
does 50% more work than Joel. 


Joel
does 75% more work than Jerry. 


Neither
of them do any work. 




Which of the following graphs illustrates Hooke's Law (the spring force)? 
















A simple pendulum, consisting of a mass m and a string, swings upward, making an angle q with the vertical. The work done by the tension force is 


zero. 


mg. 


mg
cos q. 


mg
sin q. 




What is the mass of the pendulum 'bob' in the figure? 


1
kg 


2
kg 


3
kg 


5kg 




What is the total mechanical energy, ME, of the pendulum? 


0
J 


4.9
J 


9.8
J 


14.7
J 




What is the maximum kinetic energy of the pendulum? 


O
J 


4.9
J 


9.8
J 


14.7
J 




What is the potential energy, PE, at point B and D? 


0
J 


4.9
J 


9.8
J 


14.7
J 




At point B and D what is the relationship between the kinetic energy, KE and the potential energy, PE? 


KE<PE<
TD> 


KE=PE 


KE>PE 




What is the speed of the pendulum at point B and D? 


0
m/s 


2.2
m/s 


3.1
m/s 


4.4
m/s 




What is the speed of the pendulum at point C? 


0
m/s 


2.2
m/s 


3.1
m/s 


4.4
m/s 




A simple pendulum, consisting of a mass m, is attached to the end of a 1.5 m length of string. If the mass is held out horizontally, and then released from rest, its speed at the bottom is 


4.4
m/s 


5.4
m/s 


9.8
m/s 


17
m/s 




A 4kg mass moving with speed 2 m/s, and a 2kg mass moving with a speed of 4 m/s, are gliding over a horizontal frictionless surface. Both objects encounter the same horizontal force, which directly opposes their motion, and are brought to rest by it. Which statement best describes their respective stopping distances? 


The
4kg mass travels twice as far as the 2kg mass before stopping. 


The
2kg mass travels twice as far as the 4kg mass before stopping. 


Both
masses travel the same distance before stopping. 


The
2 kg mass travels greater than twice as far. 




A 4kg mass moving with speed 2 m/s and, an otherwise identical, 2kg mass moving with a speed of 4 m/s, are gliding over a horizontal surface with friction and are brought to rest by it. Which statement best describes their respective stopping distances? 


The
4kg mass travels twice as far as the 2kg mass before stopping. 


The
2kg mass travels twice as far as the 4kg mass before stopping. 


Both
masses travel the same distance before stopping. 


The
2kg mass travels greater than twice as far. 




A force that object A exerts on object B is observed over a 10second interval, as shown on the graph. How much work did object A do during that 10 s? 


Zero 


12.5
J 


25
J 


50
J 




A force that object A exerts on object B is observed over a 10second interval, as shown on the graph. What is the average power output of A into B? 


O
W 


1.3
W 


2.5
W 


5
W 




The resultant force you exert on a shopping cart, for a 10 s period, is plotted on the graph, shown. How much work did you do during this 10 s interval? 


Zero 


12.5
J 


25
J 


25
J 




The resultant force you exert on a shopping cart, for a 10 s period, is plotted on the graph, shown. Which of the following statements are true? 


The
average power input into B is greater than zero. 


The
average power input into A is the same in the first half as the power input
in the second half. 


The
average power equals the instantaneous power. 


The
average power is zero. 




How much work was required to bring the 1000kg roller coaster from point P to rest at point Q at the top of the 50 m peak? 


32,000
J 


50,000
J 


245,000
J 


490,000
J 




If the roller coaster leaves point Q from rest, how fast is it traveling at point R? 


22.1
m/s 


31.3
m/s 


490
m/s 


980
m/s 




If the roller coaster leaves point Q from rest, what is its speed at point S (at the top of the 25m peak) compared to its speed at point R? 








2 


4 




What was the total work done on you by all the forces in the universe between the time just before you awoke this morning and right now? 


Don't
have a clue. 


Greater
than zero. 


Zero. 


Can
not be calculated. 




Two cars, starting from rest at the same place, travel by different routes to the same destination. One of the cars passes the other as they drive through it. Which of the following statements will be true? 


The
work done by friction during the trip was the same for both. 


The
total work done on both is the same. 


The
work done by gravity is the same on both. 


The
work done by gravity on both is positive. 




The work done by friction, f, 


equals
fd, where d is the total distance moved. 


equals
fd, where d is the total distance. 


can't
easily be calculated because it depends on the angle between f and d. 


can't
easily be calculated. 




A 102 kg man climbs a 5.0 meter high stair case at constant speed How much work does he do? 


510
J 


49
J 


5000
J 


2500
J 




A ball is released, from rest, at the left side of the looptheloop, at the height shown. If the radius of the loop is R and there is no friction, what vertical height does the ball rise to on the other side? (LOOPTHELOOP) 


Less
than R 


R 


2R 


Greater
than 2R 