Momentum of Tennis Ball Question

In summary, a tennis ball with a mass of 110g was traveling 18.5 m/s east and was struck by a racquet applying a force of 950 N west for 3.2ms. Using the concept of impulse, the change in momentum of the ball was found to be 3.04 kg m/s, west. The change in velocity can also be calculated using the initial velocity and the change in momentum. The initial assumption of the change in velocity being equal to 37 m/s was incorrect due to the velocity being different upon rebound.
  • #1
The Matador
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0

Homework Statement


A tennis ball with a mass of 110g is traveling 18.5 m/s east. It is struck by a racquet that applies a force of 950 N west. The ball and the racquet are in contact for 3.2ms. The change in momentum of the tennis ball is..

Homework Equations


As far as I can tell p=mv and p=w/t are relevant to the equation

The Attempt at a Solution


At first I tried to find the sum of the momentum before and subtract it by the sum of the momentum after, but that didn't seem to work. So I'm not really sure. Momentum has been my worst unit all year.

Any help would be appreciated. Thanks
 
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  • #3
So I figured if impulse is equal to the change in momentum then I could use the force and time in the equation to get the change in momentum.

so 950(3.2/1000) = 3.04

Which is the correct answer apparently (3.04 kg m/s, west).

What I'm still puzzled by is there is so much more info in the question. It appears to me that the velocity is not factored in at all. Should not mv = Ft ? (supposed to be a change in velocity, I can't find a triangle icon) Or is the change in velocity not 37m/s.
 
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  • #4
There's an important thing to remember; the change in momentum of an object is equal to the impulse [force] acting on it.
 
  • #5
The Matador said:
So I figured if impulse is equal to the change in momentum then I could use the force and time in the equation to get the change in momentum.

so 950(3.2/1000) = 3.04

Which is the correct answer apparently (3.04 kg m/s, west).
Right. Momentum is a vector, so direction is important.

What I'm still puzzled by is there is so much more info in the question. It appears to me that the velocity is not factored in at all. Should not mv = Ft ? (supposed to be a change in velocity, I can't find a triangle icon) Or is the change in velocity not 37m/s.
Since you've found the change in momentum you can easily find the change in velocity (since you know the mass of the tennis ball) using:
[tex]\vec{F}\Delta t = m \Delta \vec{v}[/tex]
But how did you get 37 m/s?

And once you correctly find the change in velocity, you can use the intial velocity to find the final velocity.
 
  • #6
K thanks for clarifying that for me.

It was more of a brain fart on my part, I realized you can find the change in velocity using the equation, but it was different then what I guessed because the ball was initially going at 18.5 m/s then I figured it would be rebounding back 18.5 m/s so I thought the change in velocity would be 37 m/s. Which is in fact wrong. The velocity coming back is not going to be the same as it was when it hit the object.

Thanks for your help guys. I had a couple similar questions on a quiz in class today and got them correct.
 
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1. What is momentum?

Momentum is a measure of an object's motion, determined by its mass and velocity. It is defined as the product of an object's mass and its velocity.

2. How is momentum calculated?

Momentum is calculated by multiplying an object's mass (m) by its velocity (v). The equation is p = m * v, where p is momentum, m is mass, and v is velocity.

3. How does the momentum of a tennis ball change during a game?

The momentum of a tennis ball can change during a game due to various factors, such as the force applied by the player's racket, the spin on the ball, and the air resistance. As the ball is hit by the racket, its velocity and direction change, causing its momentum to change as well.

4. Does the momentum of a tennis ball affect its bounce?

Yes, the momentum of a tennis ball has a direct impact on its bounce. The greater the momentum of the ball, the higher it will bounce. This is because a higher momentum means the ball has more energy, which is converted into kinetic energy upon impact with the ground, resulting in a higher bounce.

5. Can the momentum of a tennis ball be conserved?

According to the law of conservation of momentum, the total momentum of a closed system remains constant. In a game of tennis, the ball and the racket make up a closed system, so the momentum of the ball can be conserved if there are no external forces acting on it, such as air resistance.

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