QUIZ 5  “Nota”  means none of the above

 

 

  1. When the velocity of an object is tripled, by what factor is the kinetic energy (KE)  changed ?    
  (a) 1/3 (b)  9  (c) 3 (d) nota


 2. What produces the greater change in KE of  a box: exerting a 9-N force on the box for a distance of 5.5 m , or exerting a 25–N force on the box  for  a distance of 2.0 m ? Assume the force points in the same direction as the  motion.

 (a) exerting a 9-N force for a distance of 5.5 m    (b) exerting a 25–N force for a distance of 2.0 m     (c) both the same  (d) nota

 

3. Suppose a box experiences a net force of 12 N  over a distance of  1.0 m. The force points in the same direction as the motion. The change in KE is    

 

(a)  12 N  (b) 12 J  (c) - 12 J  (d) nota

 

4. Suppose a moving box experiences a net force of 12 N  over a distance of  1.0 m. If  the force points opposite the direction of the motion,  the change in KE is    

 

(a) -12 N (b)  12 J  (c) 11 J  (d) - 12 J  (e) nota

5. Suppose a box experiences a  force of  2 N  over a distance of  1.0 m. The force points in the same direction as the motion. The mass of the box is 1.0 kg.  Assume the box starts from rest.  What is the speed at the end of the motion?      

 (a) 4 m/s   (b) 2 m/s  (c) about 1.41 m/s (d) nota

6. Suppose a 1.0 kg-box is dropped from rest from a height h = 0.80 m above the ground.      Assume g = 10.0 m/s2 .  What is the work done by the gravitational force?
(a) - 8.0 J  (b) 8.0 J  (c) 10.0 J (d) nota

7. What is the speed of the box just before impact with the ground?
 

(a) 2.0 m/s (b) 8.0 m/s  (c) 4.0 m/s  (d) nota
 

8.  Suppose the  1.0 kg-box in the previous problem  is dropped from rest from the same height h = 0.80 m.  But assume an air-resistance force of magnitude R = 1.0 N acts in a direction opposite the downward motion.    What is the change in kinetic energy   of the box just before it   hits the ground?  Assume g = 10.0 m/s2 .
 

(a)  7.0 J  (b) 6.0 J  (c) 7.2 J  (d) nota


9.  A what point in its motion is the KE of a pendulum a maximum?

  (a) at the highest point    (b) at the lowest point  (c) nota

 

10. A what point in its motion is the PE (potential energy)  of a pendulum a maximum?

  (a) at the highest point    (b) at the lowest point  (c) nota

 

11.  Suppose a circus diver drops herself from the top of a tower of height H above the ground.  She starts from rest.   At the top,  her potential energy is 8,000 J. What is her kinetic energy when she reaches a height H/4 above the ground?

(a) 2000 J  (b) 6000 J  (c) 4000 J  (d) nota