# Conservation of mechanical energy problem

Problem: the masses of the javelin, discus, and shot are .8 kg, 2.0 kg, and 7.2 kg, respectively, and record throws in the track events using these objects are about 89 m, 69 m, and 21 m, respectively. Neglecting air resistance, (a) calculate the minimum initial kinetic energies that would produce these throws and (b) estimate the average force exerted on each object during the throw, assuming the force acts over a distance of 2 m. The answer is (a) 349 j, 676 j, 741 j (b) 175n , 338 n, 371n

Relevant equations: KEi+PEi=KE+PEf

Or 1/2mv^2+mgy= 1/2mv^2+mgy

Attempt: I tried to use some kind of substitution to find v and y but I only had one equation so I couldn’t use the substitution method.

http://ift.tt/1ffl5RD

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