Download More Energy Practice Problems

More Energy Practice Problems
1. A 6.4 kg bowling ball is lifted 2.1 m into a storage rack. Calculate the increase
in the ball’s potential energy.
2. A 2 kg object initially at rest loses 400 J of potential energy while falling to the
ground.
a. Calculate the kinetic energy that the object gains while falling.
b. What is the object’s speed just before it strikes the ground?
3. A 30.0 kg gun is standing on a frictionless surface. The gun fires a 0.50 kg
bullet with muzzle velocity of 310 m/s. What is the kinetic energy of both the
bullet and the gun after firing?
4. A 14700 N car is traveling at 25 m/s. The brakes are suddenly applied and
the car slides to a stop. The average braking force between the tires and the
road is 7100 N. How far will the car slide once the brakes are applied?
5. The regulation height for womens’ high hurdles for high school competition is
84 cm. With what speed must a female hurdler leave the ground to clear the
hurdle at a speed of 1.0 m/s?
6. It is not uncommon on the service of a professional tennis player for the
racquet to exert an average force of 150 N on the ball. If the ball has a mass of
0.600 kg, and is in contact with the strings of the racquet for 0.030 s, what is the
kinetic energy of the ball as it leaves the racquet?
7. A body of mass 100 g is attached to a hanging spring whose force constant is
10 N/m. The body is lifted until the spring is in its unstretched state. The body is
then released. Calculate the speed of the body when it strikes a table 15 cm
below the release point.
8. A 10 kg packet is fired vertically to a height of 637 km above the earth’s
surface. Find the weight and potential energy at its maximum altitude.
9. After being hit, a golf ball starts out with a velocity of 130 ft/s. If it reaches a
maximum height of 180 ft, what is its velocity at that point?
10. A block slides down an incline with a 45° angle that is frictionless. The
incline is 1.0 m high. When the block gets to the bottom of the incline, it reaches
a level plane which in not frictionless and stops after traveling 3.0 m.
a. What is the velocity of the block when it reaches the incline?
b. What is the coefficient of friction?
Answers
1. 130 J
2. a. 400 J
6. 170 J
7. 0.831 m/s
10. a. 4.43 m/s
b. 20 m/s
b. 0.33
3. 426 J
8. 81 N, 57 MJ
4. 66 m
9. 73.3 ft/s
5. 4.1 m/s