Explain how a parachutist's loss of momentum on landing is consistent with the principle of conservation of momentum?
The principle of conservation of momentum states that the total momentum of an isolated system remains constant if no external forces act on it. In the case of a parachutist landing, the loss of momentum is consistent with this principle.
To understand this, let's discuss the momentum involved in the situation. Momentum is defined as the product of mass and velocity; it is a vector quantity that represents an object's "quantity of motion". When the parachutist is in freefall, they have a certain amount of momentum due to their mass and initial velocity.
However, as the parachutist reaches the ground, they eventually come to a stop. This process of stopping is accompanied by a loss of momentum.
Here's how the conservation of momentum applies in this situation:
1. Initially, when the parachutist is in freefall, their momentum is at maximum (momentum_1).
2. As the parachutist's body comes into contact with the ground, an external force (the ground) acts on them to bring them to a stop. This force increases over a short period of time, causing a deceleration.
3. According to Newton's third law of motion, for every action, there is an equal and opposite reaction. In this case, the parachutist exerts a force on the ground, and the ground exerts an equal and opposite force on the parachutist.
4. The force exerted by the ground causes a negative acceleration, reducing the parachutist's velocity to zero. As a result, the parachutist's momentum decreases to zero (momentum_2 = 0).
5. Since the force exerted by the ground is an external force, acting for a short period of time, it doesn't affect the overall momentum of the system. The isolated system, in this case, is the parachutist and the Earth.
6. Therefore, the fact that the parachutist's momentum decreases to zero on landing is consistent with the conservation of momentum. The initial momentum (momentum_1) is equal to the final momentum (momentum_2 = 0), indicating that no momentum is gained or lost in the overall system.
In conclusion, the loss of momentum on landing is consistent with the principle of conservation of momentum, as the external forces acting on the parachutist bring them to a stop without affecting the overall momentum of the system.