Question

The momentum of a body of Mass 4kg is 32kgm per s It's velocity is​

Answer 1

Before the force is applied we know

momentum=mass×velocity=10 kg m/s

Since mass in the above is 5 kg, then velocity = 2 ms−1

We can now work out kinetic energy, KE:

KE=12mv2=12⋅5⋅22=10 J

The force of 0.2 N is now applied in the direction of travel for 10 seconds. Newton's second law can be expressed as "the force applied equals the rate of change of momentum". OR

F=mv−mut=m⋅v−ut

Where v is the final velocity after applying force, and u is the initial velocity ( 2 ms−1 in this case from above)

So

0.2=5⋅(v−2)10

rearranging helps us find v

2=5⋅(v−2)

25=v−2

v=125 ms−1

Hence final kinetic energy, KE, is

KE=12mv2=12⋅5⋅(125)2=14.4 J

So the overall change in KE is

ΔKE=14.4−10=4.4 J

Answer 2

Answer:

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