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FDB for TENNIS

  • Thread starter vysis
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28
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1. Homework Statement


for an FDB of an tennis ball hitting the racquet. Is the F(a)=F(n) or is F(a) larger then F(n).



3. The Attempt at a Solution

I think that F(a) = F(n). According to Newton's second law, they both receive the same force, however since the tennis ball has less mass, it receiver a larger acceleration then the tennis racquet (which is also anchored by the player's arm).

Im pretty sure im right, but it's always good to be sure.
 

Answers and Replies

PhanthomJay
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1. Homework Statement


for an FDB of an tennis ball hitting the racquet. Is the F(a)=F(n) or is F(a) larger then F(n).
What do you mean by F(a) and F(n)?
3. The Attempt at a Solution

I think that F(a) = F(n). According to Newton's second law, they both receive the same force, however since the tennis ball has less mass, it receiver a larger acceleration then the tennis racquet (which is also anchored by the player's arm).
This is not Newton's 2nd law.
Im pretty sure im right, but it's always good to be sure.
Draw a FBD of the ball, not the racquet. What forces act on the ball? The problem is not asking for acceleration.
 
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What do you mean by F(a) and F(n)?
F(a) = applied force
F(n) = Normal force

This is not Newton's 2nd law.
umm, yea sry. I was typing a bit too quickly. Third and Second law.

Draw a FBD of the ball, not the racquet. What forces act on the ball? The problem is not asking for acceleration.
nono, i mean if a tennis racquet was to hit a tennis ball. Would the applied force and normal force be equal or would applied force be larger?
 
PhanthomJay
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Neglecting the weight of the tennis ball, when the racquet hits the ball, there is only one force acting on the ball...the force of the racquet on the ball, which i guess you are calling an applied force, F(a),which is fine. Now by F(n), I think you mean the force of the ball on the racquet?
 
28
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yea, the equal and opposite force excerted on the racquet stated by the 3rd law.
 
PhanthomJay
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yea, the equal and opposite force excerted on the racquet stated by the 3rd law.
Well, you just answered your question!
 
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lol, so to sum it up:

force exerted on ball = force exerted on racquet.
However, ball flies away extremely quickly and racquet doesnt is becaue racquet is heavier and therefore according to Newton's second low, it doesnt accelerate as much (and also since the racquet is anchored to the player's hands)
 
PhanthomJay
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lol, so to sum it up:

force exerted on ball = force exerted on racquet.
Correct! (equal but opposite in direction...force exerted on ball by racquet = force exerted on racquet by ball)
However, ball flies away extremely quickly and racquet doesnt is becaue racquet is heavier and therefore according to Newton's second low, it doesnt accelerate as much (and also since the racquet is anchored to the player's hands)
Sort of. The acceleration of the ball will be in the direction of the average impulse force (which you refer to as the applied force), in accordance with Newton 2. The racquets acceleration (deceleration) is a much more complex phenomenon because of the additional varying force acting on it from the player, and the impulsive nature of the event, but it is still Newton 2 at work.
 
Last edited:
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thank you so much
 

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