Final answer:
When an object hits a barrier and stops, the impulse is the change in momentum assuming the final momentum is zero. For an object that bounces, the impulse is greater because it includes the change in momentum from stopping and reversing direction. The impulse can be calculated using an average effective force when actual forces vary over time.
Step-by-step explanation:
The impulse that acts on a moving object when it stops after hitting a barrier is the object's change in momentum during the collision. For a non-elastic collision where the object stops, the impulse can be calculated using the initial momentum and recognizing that the final momentum is zero. For example, if we have a 1.2-kg block moving at 3.0 m/s that stops after hitting a barrier, the initial momentum (Pinitial) is -3.6 kg·m/s, signifying that the block's initial velocity was negative (opposite to the direction of the force exerted by the barrier). Since the block comes to a stop, its final momentum is zero, and the impulse is equivalent to the change in momentum, which is 3.6 kg·m/s in the positive direction.
If the object bounces off a barrier, like a ball bouncing off the floor, the impulse involves a change in momentum that includes the reversal of direction, effectively doubling the change in momentum compared to an object that simply stops. The impulse is not only about bringing the object to rest but also propelling it back in the opposite direction, resulting in a greater change in momentum compared to the scenario where the object stops. As such, the impulse on a bouncing object is larger.
It is important to note that while the collision impulse is the same in magnitude and opposite in direction for two interacting bodies according to the conservation of momentum, the effects of the impulse may vary, such as differences in the change in kinetic energy when the collision is not elastic. Additionally, real-world forces are not constant, but we can use an average effective force (Feff) to simplify calculations and make it analogous to a time-varying force, where the area under the curve in a Force versus Time graph represents the impulse.