AP Physics C: Mechanics / Unit 4: Linear Momentum
4.2 Change in Momentum and Impulse
Notes
$$J=F\Delta t=\Delta p$$
- Impulse is the area under a force-time graph.
- Airbags increase $\Delta t$ to reduce force for the same $\Delta p$.
Practice
A 100 N force for 0.2 s gives an impulse of:
$F\Delta t$.
Airbags reduce injury by:
Same impulse, smaller force.
A 0.5 kg ball goes from 10 m/s to −10 m/s (bounces). $|\Delta p|=$
$0.5\times20$.
$F(t)=4t$ N from $t=0$ to $t=3$ s. Impulse:
$\displaystyle \int_0^3 4t\,dt$.
Ready for more? Take the Unit 4 test.