Question

A force of 10 N acts on a body of 2kg for 3 seconds.find the kinetic energy acquired by the body in 3 seconds.

Answer 1

If initial velocity is zero
u = 0
WKT   F= ma 
then 
10N = 2* (v-0)/3   (pls  simplify by ur self)
⇒v=15 m/s
then K.E. = [1/2] * m *  $v^{2}$ 
K.E. =  [1/2] * 2 * 15²
K.E. = 225j

Answer 2

Given : force =10 N ..Mass = 2kg ....Time = 3s........ To find :- Kinetic energy............ Sol :- E (K) =1/2 ×m ×v (sq.).......... ..Let us find the acceleration for this object.......... Force = mass × acceleration. .....acceleration = force / mass....... = 10/2 = 5m/s....acceleration = 5 m/s......... Now find the velocity...... v = u-v / 2........so, we get as V= 0-5/2....= 5/2...= 2.5 m/s....is the velocity..... Now E (K) = 1 / 2 × M × V ( SQ)..... 1/2 × 3 × 2.5 ...= 3.75 joule..!!