Group: Name(s) Date:
Impulse in Real Collisions
We have discussed Conservation of Momentum when a system is isolated so that the Net External Force is zero. This is rarely true in the real world. Here you can determine how to deal with such real situations.
One ball collides with another ball in the air above your head. The system will be the two balls, and the collision is one dimensional. Two forces that act on the top ball are shown in the graph below,
-- an external force of gravity, constant downward -2.0 N and
-- an internal collision force approximated as a triangle with a peak value of 1000 N that acts from 5.00 to 5.01 sec. (The sketch is NOT to scale!)
| Time Interval (s) |
Impulse of Collision force (N.s) |
Impulse of gravitational force (N.s) |
| 5.00 to 5.01 |
||
| 4.00 to 6.00 |
||
| 0.00 to 10.00 |
Under what conditions can we neglect the impulse of the non-zero external force?