Question

A force of 10N acts for 20 second on a body of mass 2kg initially at rest.Calculate the energy required by the body and the work done by the applied force

Answer 1

I couldn't understand Calculate the energy required by the body , I think it will Be acquired ,

Principle: Work Energy Theorem + Kinematic
F/m= a= 5m/s²
u=0 , t=20
v= 5m/s² * 20 s
v= 100m/s

change is Kinetic Energy is The Energy acquired
change in KE = KEf-KEi
(KEi = 0 as it was initially at rest )
so ∆KE= 1/2 * 2kg * 10000 m²/s²
so ∆KE = 10000kgm²/s² = 10000J
but we Know Work done by all forces = ∆KE = 1000J
that's it

Answer 2

Answer:

Given data-  m = 2kg, F = 10 N, t = 20 s, Calculate E =? And W =?

 F = ma  ⇒ a= F/(m )=10/2=5 m/s2    

 V = u + at = 0 + 5×20=100 m/s      

               E = 1/2  mv^2=1/2  ×2×〖(100)〗^2=10000 J  

 W = Fs  

 s = ut +  1/2 at^2 = 0 (20) + 1/2×5〖×(20)〗^2 = 1000 m

 W = 10 ×1000=10000 J

Explanation: