Centripetal Force Skater Speed Question

AI Thread Summary
To find the speed of the skater's hands, the distance between them, 152 cm, is considered the diameter of the circle traced by their tips. The radius is therefore 76 cm. The angular velocity was correctly converted to 23.56 rad/s. Using the formula v = wr, where v is linear speed, w is angular velocity, and r is radius, the speed can be calculated. The discussion highlights the importance of correctly identifying the radius in circular motion problems.
jibjab
Messages
13
Reaction score
0

Homework Statement


A skater holds her arms outstretched as she spins at 225 rpm. What is the speed of her hands if they are 152 cm apart?

The Attempt at a Solution


I converted 225 rpm to 3.57 rps and found the angular velocity (23.56 rad/s) to plug into the equation v=wr, but it didn't work. What would that distance between her hands be considered? I bet this is rediculously easy but I can't figure it out! Thanks in advance!
 
Physics news on Phys.org
As she spins, the tips of her hands trace out a circle, the diameter of which is the distance between her two hands.
 
Last edited:
Ah thank you!
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Back
Top