Download your brother`s speed: 1.57 m/s

Centripetal Force Problem Set 2
𝑚𝑣 2
𝐹𝑐 =
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𝐶 2π𝑟
𝑣= =
𝑇
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1) On a merry go round you sit on the outside horse 4.5 meters from the center
because from experience you know that it is the best horse for daredevils
who like to feel the wind in their hair. Your little brother sits on the furthest
inside horse 1.5 meters from the center. It takes each of you 6 seconds to
make one revolution.
a. Calculate the frequency of rotation for you and your little brother.
Why are they the same number?
b. Calculate the speed of each you and your brother. Why do you have a
greater speed?
2) Standing on the equator Jimmy has a radius of rotation around the earth,
which is equal to the earth’s radius, 6.378 x 106 m. Alice standing near the
North Pole has a radius of rotation of only 5 m, because she is so close to the
earth’s axis of rotation. Calculate the speed of Alice and the speed of Jimmy
due to the earth’s rotation. What is Alice’s speed if she stands on the North
pole?
3) Your clothes that are plastered to the wall of the washing machine during the
spin cycle. The clothes make a complete revolution around a .619 m diameter
circle in 0.285 seconds. Calculate the speed with which the clothes move.
Which type of Force is the centripetal Force on the clothes?
4) A roller coaster car is traveling over the crest of a hill and is at the location
shown. A side view is shown below. Draw an arrow on the diagram to
indicate the direction of the velocity vector.
5) Two cars each of mass 2500 kg make a turn and are provided the same force
of friction by the ground of 14700 N. If the car first makes the turn sharply
with radius 5 m and then wider with radius 12 m. For the sharp turn what
max speed can the car get? For the wide turn what max speed can the car
get? Explain why the car can achieve more speed on a wide turn.
6) On a playground carousel Lily sits on the metal surface and does not hold
onto any of the bars. She makes a turn every 2 seconds and is .8 m from the
center of the carousel. She has a mass of 25 kg. What Frictional Force is she
provided during her turn?
7) On a gravitron ride Hank’s back is up against the wall. He feels the wall
pushing on his back with a Normal Force just as if he was lying on the
ground. The gravitron makes a turn every 3 seconds and its radius is 3
meters. He has a mass of 70 kg. How much Normal Force is Hank provided
by the wall?
Answers:
1) a. .17rev/s
b. your speed: 4.71 m/s
your brother’s speed: 1.57 m/s
2) Jimmy’s speed 463.82 m/s
Alice’s speed: 3.64 x 10-4 m/s
3) 6.82 m/s
5) radius of 5 m: max speed is 5.42 m/s
radius of 12 m: max speed of 8.4 m/s
6) 197.39 N
7) 921.16 N