Question

Derive expression change in momemtum is called force

Answer 1

Answer:

Correct Question:

The rate of change in momentum is called force.

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Method (I)

P is the momentum

» Rate of change in momentum = (Pf - Pi)/t

Therefore, dimensions of the rate of change in momentum are [M¹ L¹ T-²]

Also, dimensions of force are [M¹ L¹ T-²]

Hence, F = (Pf - Pi)/t

Is the required expression.

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Method (II)

» F = ma

Here m is constant.

» We know, a = (v - u)/t

Now, F = m (v - u)/t

Momentum is given by P = mv

Therefore, F = (mv - mu)/t

But, v is final velocity and u is initial velocity. Hence mv will be final momentum (Pf) and mu will be the initial momentum (Pi).

Therefore, F = (Pf - Pi)/t

Is the required expression.