Explore the Relatioship Between the Momentum and Impulse of an Object
What do you think will happen if you throw a raw egg as hard as you can at a blanket held vertically? There is really only one way to find out. This experiment gives you an opportunity to explore the relationship between momentum and impulse.
What You Need
- 1 raw egg
- 3 people
- mop and paper towels for cleanup (very optional)
- Hold the blanket vertically, with the bottom edge curled out to form an overhang, as shown in Figure 54-1. This requires at least two people.
- The third person throws the egg at the blanket. Don't hold back. Give it a good shot. You can throw as hard as you can without having the egg break in your hands as you throw.
You know what will happen if you throw a raw egg against a cinder-block wall. However, if the egg is stopped by the blanket, the deceleration occurs over a sufficiently long time, which prevents the egg from breaking.
Why It Works
Momentum is changed by a force exerted over time. The ability to change an object's momentum is called impulse, which is defined as the force exerted multiplied by the time. Anytime an object is brought to rest, the change in momentum equals the momentum the object had to start, applied in the opposite direction. The impulse to bring that object to rest can come from any combination of force and time, which when multiplied, equal the momentum change.
If the object's momentum changes in a short time, which would occur if an egg is thrown at a cinder block wall, the force is greater. However, if the egg is thrown at a blanket that brings the egg to a stop over a much longer period of time, the force is much smaller. This is why the egg does not break when it's throw, at a blanket.
Other Things to Try
Check out the ESPN video Relaxing with Momentum that shows what happens if you drop a watermelon from a diving board onto concrete, compared with dropping a watermelon into the water.
The momentum to stop an egg thrown against a wall and a blanket is the same. However, the force in the case of the blanket is spread over a greater time and is much smaller.
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