Question

state and prove work energy theorem 3 marks question​

Answer 1

The work-energy theorem states that

“the net work done by the forces on an object equals the change in its kinetic energy.”

Proof:

According to the equations of motion,

v² - u² = 2as

Where, v = final velocity of the object

u = initial velocity of the object

a = constant acceleration

s = displacement of the object

We can also write the above equation as,

v² = u² + 2as

By multiplying both sides of the equation by m/2,

1/2 mv² - 1/2 mu² = mas

we know that 'F=ma' According to Newton's second law, we get

1/2 mv² - 1/2 mu² = Fs

we also know that W = Fs and KE = 1/2 mv²

So, we can also written as

KE (f) - KE (i) = W

∆KE = W

★ Hence proved.