Momentum and Collisions Momentum and Impulse

Linear Momentum Momentum – a vector quantity defined as the product of an object’s mass and velocity Momentum = mass * velocity p=mv Measured in kilogram-meters per second (kgm/s)

Linear Momentum You can think of momentum as a measurement of how difficult it is for an object to stop its motion Large objects have more momentum than small ones Fast objects have more momentum than slow ones

Impulse-Momentum Theorem Changes in momentum take force and time For situations involving constant force, we can use the Impulse-Momentum Theorem Force * time interval = change in momentum FΔt=Δp or FΔt=Δp=mvf-mvi

Impulse-Momentum Theorem Impulse – for a constant external force, the product of the force and the time over which it acts on an object Represented by Force * time interval FΔt or J Unit is kg*m/s Used to explain the importance of follow-through in such as pool or baseball By keeping the bat in contact with the ball longer, more force is applied to the baseball

Impulse-Momentum Theorem Use the impulse-momentum theorem to determine stopping time and therefore stopping distance with the following equation: Distance = average velocity * time interval Δx=½(vi+vf) Δt Objects with more mass require greater stopping times and distances than objects with less mass

Impulse-Momentum Theorem

Impulse-Momentum Theorem Changes in momentum over longer time periods require less force Use of safety nets and giant air mattresses by firefighters or trampolines

Impulse-Momentum Theorem