Impulse & Momentum

Momentum (p) is defined to be the mass of an object multiplied by it's velocity.

It follows then that an ocean liner can have a very large momentum even if it is moving very slowly because of it's large mass.

Conversely, a relatively small object, like a bullet, can have a large momentum due to its high velocity.

The units of measure for momentum are the same as it compoment parts:

(kgm/s)

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Impulse (J) is defined as a change of momentum (Δp).

Impulse (J) is ALSO defined as the amount of force applied to an object over time (FΔt).

It is frequently helpful to take advantage of those two equations by setting them equal to each other.

J = Δp and J = FΔt

SO

Δp = FΔt

Examining the physics of the situation (and rearranging terms):

  • We see that the amount of time it takes to change the momentum of an object is directly (although inversely) related to the force exerted on that object:

What other relationships can you determine?

Δp/F = Δt

In otherwords, when the change of momentum is large, it takes a larger force to change that momentum in a short period of time.

  • We also see that the amount of force required to change the momentum of an object increases when the time decreases.

F = Δp/Δt

What other relationships can you determine?

 

 

 
 

     

HOMEWORK: 

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