Linear Momentum Lab Activity
Page 9 of 12
As we have seen, if a system is closed, i.e., if zero total outside force acts on the system, then the total linear momentum of the system will not change. But, what happens if we want to change the momentum of a system? How can we do that?
For example, imagine an egg is flying towards you and you want to stop the egg before it is able to crash into you. Of course, you will put out your hand and catch the egg. When you catch the egg (and make it slow down and stop), you must exert a force on the egg. Let's say the system we are considering is the egg only. In this case, the egg is NOT a closed system because you are external to the system and are exerting a non-zero net force on the system.
The total linear momentum of a system can change only if a non-zero external net force acts on the system over some time. We say that an impulse must be imparted upon a system in order for the total linear momentum of the system to change.
For example, imagine an egg is flying towards you and you want to stop the egg before it is able to crash into you. Of course, you will put out your hand and catch the egg. When you catch the egg (and make it slow down and stop), you must exert a force on the egg. Let's say the system we are considering is the egg only. In this case, the egg is NOT a closed system because you are external to the system and are exerting a non-zero net force on the system.
The total linear momentum of a system can change only if a non-zero external net force acts on the system over some time. We say that an impulse must be imparted upon a system in order for the total linear momentum of the system to change.