Review Chapter 10 &11
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1. You jump onto a Slip n’ Slide and stop 2.2 m down the slide. If it took 287 J of Work to stop you, how big
is the frictional force?
2. A car strikes a wall in an accident. Luckily for the driver, his car has a high safety rating and a large crumple
zone. The car has a mass of 500 kg, and was going 15 m/s before it stopped. The crumple zone compressed
0.25 meters in 0.01 seconds.
a. What was the Force the wall exerted on the car?
b.What was the work done on the car by the wall?
3. A PE student weighs 784 N and is doing push-ups. If he raises his Center of Mass 0.32 meters every time,
how many push-ups must he do to do 2007 J of work?
4. You are running around a track at 5 km/hr and then you increase your speed to 10 km/hr. By what factor did
you increase your kinetic energy? Why?
5. A 1500 kg car traveling at 30 m/s has the same kinetic energy as a 4500 kg truck, how fast is the truck going?
6. A 2.0 x 103 kg car is pulled up a hill that is 89 m high. What is the potential energy of the car at the top of
the hill? If the car rolls down the hill what will its speed be at the lowest point, if we neglect friction?
7. An arrow of mass 0.10 kg was fired horizontally from a height of 1.5 m by an archer who exerted a force of
350 N on the bowstring and pulled the string back 0.70 m.
a. How much work is done on the arrow?
b. How much Kinetic Energy will the arrow have? How do you know?
8. A crowbar is used to open a crate. If it takes 458 N worth of force to open the crate 4 cm, enough to get it
open, how hard would a worker have to push on the crowbar if the handle is moved 0.9 m? Assume 100%
efficiency.
9. A 75 kg person, starting from rest, slides down a slide 4.0 m long and 2.3 m high. The person reaches the
bottom at a speed of 6.0 m/s. What percentage of the initial potential energy was converted to heat?
10. A 4.0 kg ball starts from rest and rolls down a hill 3.5 m high and up an adjoining hill 2.5 m high. What will
its speed be when it reaches the top of the second hill? Assume negligible friction.
11. A heavy trunk is to be loaded onto a truck by pushing it up a 3m long plank. A force of 500 N is necessary
to keep the 1000 N crate moving up the plane to a height of 1.5 m above the ground.
a. How much work is done in pushing the crate up the plank?
b.What is increase in potential energy? How do you know?
c. What is the efficiency of the system?
12. Two sticky oranges, each with a mass of 0.5 kg, are moving toward each other. One orange moves at 5.0
m/s and the other at 2.0 m/s.
a. Assuming that the oranges stick together after the collision, calculate the final velocity of the sticky mass
using momentum equations.
b.Calculate the kinetic energy before and after the collision and find out how much energy was lost.
c. What kind of collision is this?