What is the average force exerted on a bouncing steel ball?

AI Thread Summary
The discussion revolves around calculating the average force exerted on a 2.18 kg steel ball that strikes a wall at 12.6 m/s and bounces off at the same speed and angle after 0.152 seconds of contact. Participants emphasize the importance of determining the change in momentum, particularly focusing on the perpendicular component to the wall, as the parallel component remains unchanged. The impulse-momentum theorem is highlighted, indicating that the average force can be calculated by dividing the change in momentum by the time of contact. Clarifications are sought regarding the correct application of the velocity components and the implications of negative velocity upon bouncing. Understanding these concepts is crucial for accurately solving the problem.
Knfoster
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Homework Statement



A 2.18 kg steel ball strikes a massive wall at 12.6 m/s at an angle of a = 55.1o with the plane of the wall. It bounces off with the same speed and angle (as seen in the figure below). If the ball is in contact with the wall for 0.152 s, what is the average force exerted on the ball by the wall?

Homework Equations



mv/change in t = average force
v=sq. root 2gh

The Attempt at a Solution


I've tried finding the impulse and then dividing it by the .152 sec. but I keep getting the wrong answer. Could someone please walk me through the equations and steps? Thanks!
 
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Knfoster said:

Homework Statement



A 2.18 kg steel ball strikes a massive wall at 12.6 m/s at an angle of a = 55.1o with the plane of the wall. It bounces off with the same speed and angle (as seen in the figure below). If the ball is in contact with the wall for 0.152 s, what is the average force exerted on the ball by the wall?

Homework Equations



mv/change in t = average force
v=sq. root 2gh

The Attempt at a Solution


I've tried finding the impulse and then dividing it by the .152 sec. but I keep getting the wrong answer. Could someone please walk me through the equations and steps? Thanks!

What is the Δ in momentum?
 
momentum= mass(velocity)...2.18*12.6=27.5
 
Knfoster said:
momentum= mass(velocity)...2.18*12.6=27.5

But what was the Δ in momentum.

Think x,y components.
 
Resolve the initial and final velocity vectors to find out which component undergoes a change.
 
v1 prime would be -v1
v2 prime would be 0

how does that fit into the problem?
 
Knfoster said:
v1 prime would be -v1
v2 prime would be 0

how does that fit into the problem?

Impulse requires knowing the Δ in momentum.

Now not all the momentum changes here. For instance the momentum || to the wall is unchanged after contacting the wall.

But the ⊥ component has a change. Figure that change as I think you will be needing it.
 
I don't understand... Is that not just the negative of the velocity?
 
Knfoster said:
I don't understand... Is that not just the negative of the velocity?

Negative of the original velocity means that it returned in the direction it came.

It did not.
 

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