a ball of mass 2kg is thrown up with a speed of 10m/s. find the kinetic energy of the ball at the time of throwing.also find its potential energy of the ball at the highest point.[g = 10m/s].

mass               = 2 kg 
initial velocity = 10m/.s
g                     = 10m/s2 
final velocity   = 0 m/s 
kinetic energy  = 1/2m(v2 - u 2)
                         = 1/2 * 2( 02 - 102)
                         = 0-100
                          =-100 joules.
Now we know that sum of kinetic energy and potential energy is equal at any point while it is being thrown up.
The kinetic energy when the ball was thrown up is -100 joules. At this time the potential energy will be 0 as the height is 0.
Sum of potential and kinetic energy= 0 + -100 
                                                       =-100 joules.
At the highest point the kinetic energy will be 0 as the velocity is 0.
At the maximum point,
KE + PE = -100 
PE           = -100 + 0 
                = -100 joules.




 

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