Forces and Laws of Motion
Forces and Laws of Motion > Ask Alfie
Hi
Distinguish between momentum and impulse?
Difference between Momentum and Impulse:
--Calculation for Momentum vs. Impulse: The way you calculate each is completely different. You calculate the impulse of an object by multiplying its mass with its velocity, while you calculate the impulse of an object by calculating the integral of a force over a period of time, or, alternatively, by calculating the change in the momentum of a body. This also applies to any systems of more than one body, you would just need to calculate the sum of all the vectors. --Connection to force: As was mentioned above, the impulse is an integral of a force, so it can be calculated directly by knowing the force, while the momentum is used to calculate the force itself. -- Considered effects of Momentum vs. Impulse: Impulse takes into account two things – both the force that acts on a system and the duration of time for which that force acts. However, momentum only gives the instantaneous effects of the action of force on a system, in terms of the product of mass and velocity, without providing any knowledge about how that force has acted in the past. --Example of momentum: 1.A semi-truck full of logs has a large mass and must slow down long before a stop light because even with a small velocity, it has a large momentum and is difficult to stop. 2. A four-wheeler moving at a relatively fast velocity has a smaller momentum than the semi-truck because of its small mass and will stop much faster. 3. A bullet, although small in mass, has a large momentum because of an extremely large velocity. --Example for impulse: 1.Batsman hitting the ball while playing cricket. The bat is in contact with the ball for very less time but changes its course quite significantly. Kick starting a bike. 2.The kick rod applies force for a very small time during which a dynamo is rotated and a small spark is produced to start the IC engine.
--Calculation for Momentum vs. Impulse: The way you calculate each is completely different. You calculate the impulse of an object by multiplying its mass with its velocity, while you calculate the impulse of an object by calculating the integral of a force over a period of time, or, alternatively, by calculating the change in the momentum of a body. This also applies to any systems of more than one body, you would just need to calculate the sum of all the vectors. --Connection to force: As was mentioned above, the impulse is an integral of a force, so it can be calculated directly by knowing the force, while the momentum is used to calculate the force itself. -- Considered effects of Momentum vs. Impulse: Impulse takes into account two things – both the force that acts on a system and the duration of time for which that force acts. However, momentum only gives the instantaneous effects of the action of force on a system, in terms of the product of mass and velocity, without providing any knowledge about how that force has acted in the past. --Example of momentum: 1.A semi-truck full of logs has a large mass and must slow down long before a stop light because even with a small velocity, it has a large momentum and is difficult to stop. 2. A four-wheeler moving at a relatively fast velocity has a smaller momentum than the semi-truck because of its small mass and will stop much faster. 3. A bullet, although small in mass, has a large momentum because of an extremely large velocity. --Example for impulse: 1.Batsman hitting the ball while playing cricket. The bat is in contact with the ball for very less time but changes its course quite significantly. Kick starting a bike. 2.The kick rod applies force for a very small time during which a dynamo is rotated and a small spark is produced to start the IC engine.
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