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:

An object of mass 5 kg moving at 25 m/s hits a wall and comes to rest. We compare two scenarios in which it stops in 3 s and in 5 s. The impulse imparted to the object is given by the change in momentum: $$m \times \Delta v$$. In both cases the initial momentum is the same and the final momentum is zero, so the impulse is

$$J = m(v_f - v_i) = 5(0 - 25) = -125 \text{ kg m/s}$$

and its magnitude is 125 N·s.

The average force over the stopping time is calculated as

$$\frac{\text{Impulse}}{\Delta t}$$

When the object stops in 3 s, the average force is

$$F_1 = \frac{125}{3} = 41.67$$ N,

whereas stopping in 5 s yields

$$F_2 = \frac{125}{5} = 25$$ N.

Thus, although the impulse is the same in both cases, the average force differs due to the different time intervals. Therefore, the correct answer is Option B: impulse will be the same for both cases but the average force will be different.