When you jump , you automatically bend your knees. Why does this make a better jump? It is because of Impulse.
Impulse is Force multiplied by time.
Impulse = Force x time
Time in here is time in contact to relieve the force. The more time it is in contact, the less force is applied.
When you jump, you automatically bend your knees to increase the time in contact. For example, if you just stand up your contact time is 1 second, then your knees would have to endure the full force. However, if you bend your knees you make contact time 2 seconds, the force applied on your knees would be half of what it would be when you just stand up.
It is same for boxing. When a boxer punches his opponent, the opponent’s head automatically push his head backward to increase time in contact. That ways the opponent would receive less damage.
Impulse is so crucial in our life. As an example, when you are physically in danger, you should try to make the time in contact as long as possible to receive less damage.
Momentum is mass multiplied by velocity.
Momentum = mass x velocity
The most important law in momentum is conservation of momentum. Momentum is conserved at all times.
For example a ball has a mass of 3kg, and velocity of 2m/s. A ball hits another ball and stops. Then the another ball would have the same momentum as the original ball. The original ball has momentum of
3×2=6.
Therefore, if the latter ball has mass of 1kg, the ball would have velocity of 6m/s. If the latter ball has mass of 6kg, it would have velocity of 1m/s. In all ways, the momentum is conserved.
Also, momentum is a vector, so the direction is important as well. If a ball with name A was going East with mass of 5kg and velocity of 2m/s, it has momentum of 10kgm/s to East. If the ball A hits a ball B with mass of 10kg, and bounce back to West direction with velocity 1m/s. The ball B’s momentum plus the original ball’s momentum after the contact must be equal to the momentum 10kgm/s to East.
Let velocity of the ball B be x. Then,
10 = 10x – 5*1
Because the ball A goes to the opposite direction after the contact, it has momentum of negative sign.
If you solve the equation, x = 0.5m/s.
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This article was written for you by Edmond, one of the tutors with TestPrep Academy.