JEE Main · 2022 · 28 Jul 2022 · Shift 1 · Conservation of Momentum

In two different experiments, an object of mass 5 kg moving with a speed of

25 ms^{- 1}

hits two different walls and comes to rest within
(i) 3 second, (ii) 5 seconds, respectively.

Choose the correct option out of the following :

(A)Impulse and average force acting on the object will be same for both the cases.
(B)Impulse will be same for both the cases but the average force will be different.✓ Correct
(C)Average force will be same for both the cases but the impulse will be different.
(D)Average force and impulse will be different for both the cases.

Answer: (B)

Solution

Impulse equals the change in momentum:

I = Δ p = m (v_{f} - v_{i})

. Since the object comes to rest from the same initial speed in both cases,

Δ p

is identical, so impulse is the same. Average force is

F_{a v g} = \frac{Δ p}{Δ t}

. Since

Δ t

differs (3 s vs 5 s), the average forces are different. Case (i) has a larger average force.

JEE Main · 2022 · 28 Jul 2022 · Shift 1 · Single correct option