Tower 300m above the ground dropped A 1kg Hammer.how much potential energy does it have the instant it is dropped.How much kinetic energy does it have the instant right before it hits the ground.how much potential energy does it have once it hits?

1 Answer
Mar 1, 2018

While,solving this problem,we need a reference level,i.e where the potential energy is zero.

Here, we consider potential energy to be zero,so at #300 m# above the ground,the hammer had a potential energy of #mgh=1*9.8*300=2940J#

Now,while sitting on top of the #300m# high tower,the hammer had no velocity,so its total energy was potential energy.

As,it then fell on the ground only due to the effect of gravity,we can say total energy will be conserved during this process,

So,we cans write,
Total energy on top of the tower = Total energy while touching the ground

#=># Potential energy on top of the tower = Potential energy at ground + Kinetic energy while hitting the ground(K.E)

So, #K.E = 2940J# as potential energy on the ground is taken to be zero.enter image source here