How high does the ball rebound?

In summary: Calculate the impulse on the ball by the floor during the 10 ms the ball is in contact with the floor. Use the definition of impulse to find the ball's momentum just before it hits the floor. The ball will rebound with an impulse of 9.81m/s.
  • #1
edr2004
7
0
I ONLY NEED HELP WITH LETTER G. I ALREADY HAVE THE CORRECT ANSWERS FOR A-F.
I posted all of the questions so you guys can see all the information I have.

Homework Statement



A rubber ball with a mass of 200 g is released from rest from a height of 2.0 m. It falls to the floor, bounces, and rebounds. The graph at right depicts the magnitude of the upward normal force that the floor exerts on the ball at various instants in time. The graph only shows the narrow window of time surrounding the interval when the ball was in contact with the floor.

a.) How long does it take the ball to fall the 2.0 m to the floor?
b.) How fast is the ball traveling just before it hits the floor?
c.) What is its momentum just before hitting the floor (using a coordinate system in which the positive-y axis points in the upward direction)?
d.) What is the impulse on the ball by the floor during the 10 ms the ball is in contact with the floor?
e.) What is the impulse on the ball by the earth’s gravitational pull during the same 10 ms?
f.) By how much does the ball’s momentum change as a result of this 10-ms period?
g.) How high does the ball rebound?


Homework Equations


Change of momentum = mass * change of velocity
V2^2 = 2a*change of position


The Attempt at a Solution


Change of velocity = (2.4kg.m/s) / (0.2kg) = 12m/s
(12m/s)^2 = 2 (9.81m/s2) * change in position
CHange in position = (144m2/s2) / 2*9.81m/s^2 = 7.34m , which is not correct.
Also I was able to calculate Acceleration from the impulse on ball by the floor. I am not sure if and/or how I would use that acceleration.
Anyway I would appreciate any help.
 
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  • #2
I do not see your graph.
 
  • #3
I attached the graph (it will open as a Word document). For some reason I can't paste it with my message.
 

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  • #4
First things first. Answer a, b, & c: those question have nothing to do with your graph; treat the ball as any other falling body. The graph is only relevant for answering d. (For that you'll need the definition of impulse.)
 
  • #5
Thanks for replying but again I ONLY NEED HELP WITH G, which asks how high the ball will rebound. I already have the correct answers for a-f. I only posted the other questions so you guys would know what information I was given. So if you could look under my orignal post at the attempt to solve the problem and offer some suggestions I would appreiciate it.
THANKS
 
  • #6
Next time BE CLEARER. :smile:

edr2004 said:

The Attempt at a Solution


Change of velocity = (2.4kg.m/s) / (0.2kg) = 12m/s
(12m/s)^2 = 2 (9.81m/s2) * change in position
CHange in position = (144m2/s2) / 2*9.81m/s^2 = 7.34m , which is not correct.
Find the actual speed of the rebounding ball, not its change in speed. (You can use the results of f to find that rebound speed.)
 

1. What is momentum?

Momentum is a property of moving objects that describes their tendency to continue moving in the same direction at the same speed. It is calculated by multiplying an object's mass by its velocity.

2. How does height affect the rebound of an object?

The height of a rebound refers to the distance that an object bounces back after hitting a surface. The higher the object is dropped from, the greater the height of the rebound will be. This is because the object gains more potential energy as it is lifted higher, which is then converted into kinetic energy upon impact with the surface, resulting in a higher rebound.

3. What is the relationship between momentum and height of rebound?

The relationship between momentum and height of rebound is that as momentum increases, so does the height of the rebound. This is because an object with a greater momentum will have more energy to transfer to the surface upon impact, resulting in a higher rebound.

4. How does the mass of an object affect its momentum and rebound height?

The mass of an object has a direct impact on its momentum, as momentum is calculated by multiplying mass by velocity. Therefore, the greater the mass of an object, the greater its momentum and subsequently, the higher the rebound height will be.

5. Is there a limit to the height that an object can rebound to?

Yes, there is a limit to the height of rebound for an object. This is due to the law of conservation of energy, which states that energy cannot be created or destroyed, only transferred. Therefore, the total energy of an object before and after the rebound must be equal, and the object will eventually come to rest at a certain height due to the loss of energy through factors such as air resistance and friction.

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