Q. 233.7( 3 Votes )
A block of mass 5 Kg is lying on a frictionless table. A force of 20 N is applied on it for 10 seconds. Calculate its kinetic energy.
Answer :
Given,
Mass of body = 5 kg
Force F = 20 N
Time t = 10 seconds
To find: kinetic energy??
Initial velocity u = 0
Let final velocity be v
We know, 
So, acceleration = 4 ms-2
We also know that,
Substituting value of acceleration and u in this formula:
v = 10 s × 4 ms-2
v = 40 ms-1
Kinetic energy = 
m v2
Substituting value of v in the equation
Kinetic energy = 
= 4000 J
= 4 KJ
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