Question

A body starts from rest from a distance 4 from the centre of earth it reaches the surface of earth whose radius is r speed acquired by the body is

Answer 1

We will take the potential energy as the kinetic energy  

 

Potential energy is zero at infinity, it is always negative, more negative more faster.  

r = 0  

 

Potential energy at r U= -m GMe/r  

at Re this is-m GMe/Re  

the U will go from r to Re 

UatRe -Uat r =-m GMe/Re-(-m GMe/r)  

so there will be no U when it falls=  m GMe(1/Re - 1/r)  

so  

(1/2)m v^2 = G m Me(1/Re - 1/r)  

or  

v^2 = 2 G Me (r -Re)/(r Re)  

 

i hope this works if not then ,I am sure you can solve it, so try it you learn better,solving home work is one way of understanding the subject of physics.

Answer 2

Answer:hope it helps

Explanation: