# Why is it quieter to lower your hand when you catch a falling ball?

• Alexander350
In summary: OK, so to sum up, the force when moving your hand down is lower which makes a quieter sound, but the work done in both situations is equal and the loss of kinetic energy into the arm is biology so not part of the problem. Thanks.
Alexander350
If there is a ball falling from a height due to gravity, and you keep your hand still and let the ball fall onto it, it stops suddenly and makes a loud noise. However, if you lower your hand as you catch the ball, like when a cricketer catches a fast moving ball, the catch is almost silent. I understand that in the second scenario, the force exerted is lower because the change in momentum of the ball occurs in a longer time. However, since there is the same amount of GPE being transferred during the collision, why does the second one have a lot less sound energy being released than the first?

Alexander350 said:
However, since there is the same amount of GPE being transferred during the collision, why does the second one have a lot less sound energy being released than the first?

Alexander350 said:
I understand that in the second scenario, the force exerted is lower because the change in momentum of the ball occurs in a longer time

russ_watters
What causes the release of sound energy? It kind of looks to me like you answered your own question when describing its background!

davenn said:

russ_watters said:
What causes the release of sound energy? It kind of looks to me like you answered your own question when describing its background!

I can't seem to understand the relationship between the force and the energy. How can the second one have a lesser force and therefore less sound, but then the same amount of energy still get lost? Where does the energy go if it isn't sound or kinetic or GPE, and I can't imagine it being heat or anything else?

Alexander350 said:
I can't seem to understand the relationship between the force and the energy. How can the second one have a lesser force and therefore less sound, but then the same amount of energy still get lost? Where does the energy go if it isn't sound or kinetic or GPE, and I can't imagine it being heat or anything else?
You still answered that, though didn't go into the details:
...you lower your hand as you catch the ball...

russ_watters said:
You still answered that, though didn't go into the details:
Is it stored in your arm as if it were a spring, and if so, why doesn't it stretch back afterwards?

Alexander350 said:
Is it stored in your arm as if it were a spring, and if so, why doesn't it stretch back afterwards?
Well, kind of, but no; you don't let it. You have control over your muscles and making them do stuff consumes energy.

russ_watters said:
Well, kind of, but no; you don't let it. You have control over your muscles and making them do stuff consumes energy.
So isn't the energy used even more then... Why do you have to use energy to catch it but then less energy is released afterwards?

Alexander350 said:
So isn't the energy used even more then... Why do you have to use energy to catch it but then less energy is released afterwards?
All of the kinetic energy of the ball is absorbed by one thing or another (almost all by your arm) in both cases. How much energy you need to apply to your arm to make that happen is a matter of biology, not physics. It isn't actually clear to me which requires more.

russ_watters said:
All of the kinetic energy of the ball is absorbed by one thing or another (almost all by your arm) in both cases. How much energy you need to apply to your arm to make that happen is a matter of biology, not physics. It isn't actually clear to me which requires more.
OK, so to sum up, the force when moving your hand down is lower which makes a quieter sound, but the work done in both situations is equal and the loss of kinetic energy into the arm is biology so not part of the problem. Thanks.

## 1. Why is it quieter to lower your hand when you catch a falling ball?

When a ball falls, it creates sound waves as it moves through the air. When you catch the ball, your hand absorbs the energy of the ball, causing the sound waves to dissipate and become quieter.

## 2. How does lowering your hand affect the sound of a falling ball?

Lowering your hand reduces the distance between the ball and your hand, which decreases the amount of time for the sound waves to travel. This results in a quieter sound as the sound waves have less time to travel and lose energy.

## 3. Is there a difference in sound when catching a ball with a higher hand vs a lower hand?

Yes, there is a difference in sound when catching a ball with a higher hand vs a lower hand. When catching a ball with a higher hand, the distance between the ball and hand is greater, allowing for more time for the sound waves to travel and create a louder sound.

## 4. Does the speed of the falling ball affect the sound when caught with a lower hand?

Yes, the speed of the falling ball does affect the sound when caught with a lower hand. The faster the ball falls, the more energy it has, resulting in louder sound waves when caught. However, lowering your hand can still help reduce the sound compared to catching with a higher hand.

## 5. How does air resistance play a role in the sound of a falling ball?

Air resistance causes the ball to slow down as it falls, which reduces the energy of the ball and the sound waves it creates. So, even if you catch the ball with a higher hand, the sound will be quieter due to the decreased energy from air resistance. Lowering your hand can further reduce the sound by absorbing more energy from the ball.

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