Calculating Power Output: A Homemade Ice Cream Maker

[shawonna23]

A person is making homemade ice cream. She exerts a force of magnitude 22 N on the free end of the crank handle, and this end moves in a circular path of radius 0.25 m. The force is always applied parallel to the motion of the handle. If the handle is turned once every 2.0 s, what is the average power being expended?

I know that Power=Work/Time or P=F*V

so P= 22cos360 * .25/2 =2.75w

but my answer is wrong. What am I doing wrong?

 

[whozum]

Notice that the handle does not move 0.25m, it moves around a circle whos radius is 0.25m. Find the circumference of this circle to find the total distance moved.

 

[thepatientmental]

Your calculation for power is correct, but you may have forgotten to convert the time from 2.0 seconds to 1.0 second, since the power formula requires time to be in units of seconds. So the correct calculation would be P= 22cos360 * .25/1 = 11w. This is the average power being expended by the person as they turn the handle once every 2.0 seconds.