1.A 50.3-g golf ball is driven from the tee with an initial speed of 40.6 m/s and rises to a height of 29.9 m. (a) Neglect air resistance and determine the kinetic energy of the ball at its highest point. (b) What is its speed when it is 6.17 m below its highest point?(adsbygoogle = window.adsbygoogle || []).push({});

a. KE=1/2mv^2

i used this formula to find the KE but i keep getting the wrong anwer

KE=1/2(0.0503 kg)(40.6)^2=41.5 but this is the wrong answer. i;m not sure why it's wrong...

b. i used the formula:

KEinitial+PEinitial=KEfinal+PEfinal

PE initial=0 cause the initial height is 0 and KE final is 0 because the final velocity is 0. so the i get: KEinitial=PEfinal and for final height i get 11. but i don't think that i did this correctly though

2. A cyclist approaches the bottom of a gradual hill at a speed of 27.0 m/s. The hill is 7.29 m high, and the cyclist estimates that she is going fast enough to coast up and over it without pedaling. Ignoring air resistance and friction, find the speed at which the cyclist crests the hill.

i used KEinitial+PEinitial=KEfinal+PEfinal and solved for the final velocity and i got 14.8 but that is wrong

3. A person is making homemade ice cream. She exerts a force of magnitude 26.4 N on the free end of the crank handle, and this end moves in a circular path of radius 0.271 m. The force is always applied parallel to the motion of the handle. If the handle is turned once every 1.16 s, what is the average power being expended?

i think you would use the equation P=Work/Time in this problem but other than that, i'm not sure where to start.

any help on any of the problems would be great. thanks so much

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# Homework Help: Work and energy probelms

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