A phyisics question, I need to determine Kenetic Energy?
A shot-putter heaves a 7.36-kg shot with a final velocity of 7.50 m/s. (A.) What is the kinetic energy of the shot?
(B.) The shot was initially at rest. How much work is done on it to give it this kinetic energy? Note: This isn't homework, these are practice problems for a quiz, and I cannot get this one!
Update:I know all the equations but I still can't do the problem, I need to check my answers.
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Verified answer
(A)
Kinetic Energy can be found by the formula
KE = .5*m*v^2
in this case
KE = .5*7.36*(7.5)^2
(B)
We can answer this with the Work-Energy theorem. (By the way, the Work-Energy theorem is just one way of stating the law of Conservation of Energy.) The Work-Energy theorem says that the work done on a system is equal to the energy transferred to the system.
So in this case the amount of work done on the shot put is equal to the kinetic energy of the shot put. (the answer to part A)
if you ignore air resistance and assume that the shot stays level then the energy is just:
a) 1/2*mass*(velocity)^2
b) using the work-energy theorem
PE(initial)+KE(initial)+Work=PE(final)+KE(final)
canceling out what doesn't matter
PE(initial) = 0
KE(initial) = 0
PE(final) = 0
thus,
W = KE(final)