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# Momentum and Collisions - Physics Question Help Please.

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I'm sorry if this is the wrong place to post, but I am in urgent need of some physics help. Hopefully there are physicists in this forum that can help me out. Any help would be much appreciated!

1) Two football players of masses m and M are involved in an inelastic collision. The inital veloctities of the two players are 7.2m/s [E20N] and 8.1m/s [N30E] respectively. The heavier player moves Northeast after the collision. What is the mathematical relationship between the two massses?

2) A tennis racquet hits a ball initially moving at 52m/s [S70E]. Following the impact, the ball changes its direction, but not its speed. The new direction is [N70E]. If the two objects were in contact for 2*10^-3 seconds, and the mass of the ball is 180grams, what was impulse imparted on the ball?

Jan 21, 2018

### 2+0 Answers

#1
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Looked up a few things about INelastic collisions and found this webpage which may be what you are looking for in your first question:  (?)

http://hyperphysics.phy-astr.gsu.edu/hbase/inecol.html

where m1 and m2    can be   m and M  in your question....

Jan 21, 2018
#2
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I'll take a SHOT at the second question as follows..... (I'm going into things I have not seen for > 30 years...I could be quite INCORRRECT):

J= impulse = F(t2-t1) = mv2-mv1 = m (v2-v1)   (1)      (hmmmm ...doesn't appear I need the time of contact involved)

m = 180 grams

v2 = 52 sin70   +  52 cos 70

v1  = -52 sin70 + 52  cos 70

so v2-v1 = 52sin70 + 52cos70   - (-52sin70 + 52 cos 70)

= 104 sin70 = 97.728 m/s

then from (1) above        180 gm (97.728 m/s) =  17591  gm - m/s  =  17.591 kg - m/s  =17.591  N*s

(This assumes I understand the notation for direction (S70E    etc) used in your question! to look something like this: ) Jan 21, 2018