Question

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5 marks
The velocity of a body moving in a straight line is increased by applying a constant force F, for some distance in the direction of the motion. Prove that the work done by the force on the body is equal to the change in the kinetic energy of the body

Answer 1

Answer:

because

force is eqaul too mass *accelartion

and the kinetic energy is also run upon accelartion

hence proved

Answer 2

Answer:

We know that v

2

=u

2

+2as

And Work done =F×s for a constant force F.

Also we know that a =

m

F

v

2

−u

2

=2as

This gives s=

2a

v

2

−u

2

F=ma

We can write work done (W) by this force F as

W=ma(

2a

v

2

−u

2

)=

2

1

mv

2

−

2

1

mu

2

=(K.E)

f

−(K.E)

i