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

You can solve the problem in different ways:
1. find work done and that is equal to KE.
2. find velocity and then power and then work done.
3. find velocity and then KE directly.
I am using the third one.
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mass = 2kg
force = 10N
time = 3s
acceleration = F/m = 10/2 = 5m/s²
velocity = u+at = 0+5×3 = 15m/s

KE = $\frac{1}{2}mv^2= \frac{1}{2} \times 2 \times 15^2=225J$

Answer 2

given that ,
mass ( m ) = 2kg
 time ( t ) = 3 seconds 
 k.e.= ?
 u = 0 
 a = ?
 F = 10 N
v = ?
F= m * a 
  a = F / m
 a = 10 / 2 
  = 5 m/s
 v = u +at
   = 0 + 5 * 3
   = 15 m/s
k.e. = 1/2mv^2
       = 1/2*2*(15)^2
      = 225 Joules