Ings19 Posted January 4, 2013 Share Posted January 4, 2013 Hi, the question is...a body of mass 200kg is raised to a height of 5m before being allowed to fall freely. Calculate the potential energy and kinetic energy; a) before it starts to fall when it reaches the ground. i have calculated for P.E@5m = PE=m x g x h = 200x10x5 = 10kJ P.E@0m= m x g x h = 200x10x0= 0J k.e@5m= ke= (m x v2)/2 = (200x0)/2 = 0J k.e @0m= (m x v2)/2 = (200x10sq)/2 = 10KJ Quote Link to comment Share on other sites More sharing options...
0 FizziksGuy Posted January 5, 2013 Share Posted January 5, 2013 Hi Matt. That looks correct. The total energy is conserved (neglecting friction) in this problem, so at the highest point it is at rest, KE=0, and all its energy is potential energy. As it falls, the potential energy gets converted to kinetic energy, so right before it hits the ground, its potential energy is 0, and its kinetic energy is 10kJ. Once it hits the ground and comes to rest, both potential and kinetic energy are zero (note that all of these are based on the assumption that we're calling the ground level our relative zero point of potential energy). :wave) Quote Link to comment Share on other sites More sharing options...
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Ings19
Hi, the question is...a body of mass 200kg is raised to a height of 5m before being allowed to fall freely.
Calculate the potential energy and kinetic energy;
a) before it starts to fall
when it reaches the ground.
i have calculated for
P.E@5m = PE=m x g x h = 200x10x5 = 10kJ
P.E@0m= m x g x h = 200x10x0= 0J
k.e@5m= ke= (m x v2)/2 = (200x0)/2 = 0J
k.e @0m= (m x v2)/2 = (200x10sq)/2 = 10KJ
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