Centripetal Force Practice ProblemsName:
PhysicsPeriod:
1. A force that pushes forward on an object speeds the object up. A force that pushes backwards slows the object down. What effect does a force that is perpendicular to the object’s motion do?
2. What is a centripetal force?
3. For each of the following situations, identify the specific force that is providing the centripetal force:
a) A car drives around on a flat circular track
b) A child rides on a merry-go-round
c) A child is spun in a circle until their feet leave the ground
d) A child on a tire swing swings in a circular path
e) The clothes in your clothes washer go through the spin cycle
f) Your dog runs in circles around you while you hold onto the leash.
4. An 800 kg car drives with a constant speed of 50 m/s on a circular track with a diameter of 200 m.
a) How quickly is the car accelerating as it continuously turns?
b) How much centripetal force is needed to make the car turn? What specific force is providing it?
c) What is the minimum coefficient of friction to keep the car from skidding off the track?
5. A 0.0001 kg beetle stands on the turntable of a record player while it is turning at 45 rpm (revolutions per minute). The beetle is standing 10 cm from the center of the turntable.
a) What is the beetle’s speed as the turntable spins? (Hint: find the distance traveled and the time for one revolution)
b) How quickly is the beetle accelerating as it keeps turning?
c) How much centripetal force is needed to make the beetle turn? What specific force is providing it?
6. A toy airplane on the end of a 5 m long string flies in a horizontal circle at 7 m/s.
a) How quickly is the airplane accelerating as it changes direction?
b) If the tension in the string is 2.45 N, how massive is the airplane?
7. Your 30 kg dog is running at 10 m/s on the end of a 3 m leash. How hard do you have to pull on the leash to keep your dog from running away?
8. Kevin is playing on a merry-go-round in a park. He is hanging on to the railing at the edge of the merry-go-round, 1.5 m from the center.
a) If Kevin has a mass of 65 kg, and the railing pulls him in with 260 N, how fast is he moving?
b) How long will it take him to make one complete revolution around the merry-go-round? (Hint: How far does he have to travel to go around the circle?)
Challenge
9. You go on the floor drop ride in a local amusement park. In the ride, you stand along the walls of a giant drum (5 m radius), which is rotated at fairly high speed. Once you are spinning at full speed, the floor is dropped out from underneath you, but you don’t fall with it. If the coefficient of friction between you and the wall is 0.8, how fast does the drum need to be spinning for you to stay up when the floor drops? Guess your mass as best you can to use in the calculation. (Hint: Think about what force makes you spin in a circle with the drum and how that is connected to the friction.) Answer: 7.83 m/s