Question

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

Answer 1

Answer:

Correct option is

B

100 kg-m/s

F=10N,m=20kg,t=10s

a=

m

F

=

20

10

=0.5m/s

2

v=u+at=0+0.5×10=5m/s

Change in momentum =m(v−u)=20(5−0)=100kgm/s

Answer 2

Answer:

F = 10N

mass = 2kg

F = ma

a = F / m = 20 / 2 = 5m/s²

acceleration (a) = 5m/s²

time (t) = 20s

initial velocity (u) = 0

displacement (s) = ut + at²/2

s = 0 + 5×20² / 2

s= 5 × 20 × 20/2

s = 5 × 20 × 10  

s = 1000m

Work done = F × s

                   = 10×1000

                   = 10000j

v = u + at

v = 0 + 5×20

v = 100m/s

Kinetic energy = 1/2mv²

                        = 1/2 × 2 × 100 × 100

                        = 10000joules