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# Momentum watch

1. HELPP

A ball of mass 5 kg bounces on a metal plate. The collision time is 0.02.
Inital velocity of ball 6ms and rebound velocity is 4ms.
A) Find the average force exerted by ground on ball.
B) Find the TOTAL force exerted by ground

The ans to A is F= impulse/time
5(6+4)/0.02= 2500 N

I dont get how will B be done
2. How many marks is part B because with what I'm thinking its really simple but if it isn't one mark then it isn't that.
3. One
4. Are total force and average force same things?
Or for total force we should add weight?
5. Total means the resultant force.
7. (Original post by Insia786)
Pretty sure that the answer you have for A is actually for B because the resultant force is what causes the acceleration and so really the equation is giving the resultant. I have absolutely no idea what average is meant to be and the internet doesn't help apart from giving the exact same equation for both. Unless it means that the average force is just the force exerted by the floor. All I can think of is weight coming into this.

Sorry but this question just felt weird with the wording in each part. Never heard of average force at all and really total force was described as just resultant force.
8. Just thought about it and realised what it meant by average force. In the collision the force will be max on first contact and min at the end so there will be an average value and this average value would be the force if it were constant to cause the rebound in the length of time of the collision. So yeah thinking its a combination of the momentum change as well as the weight.

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Updated: April 27, 2016
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