Average magnitude of force during a 0.4 second impact

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To calculate the average force exerted on a roof by a 40kg branch falling from a height of 5.5m over an impact time of 0.4 seconds, the momentum approach is used. The momentum (P) is calculated as approximately 415 kg·m/s. Dividing this momentum by the impact time yields an average force of 1037.5 N. The initial concern about using F=ma is addressed, as it is not applicable in free fall scenarios. The final calculation is confirmed to be correct.
Crushgear64
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Homework Statement



A 40kg branch falls 5.5m and lands on a roof. The roof withstood the the impact.

Homework Equations



If the impact time was 0.4 second calculate the magnitude of the average force exerted on the roof during the impact.

The Attempt at a Solution



F=ma doesn't seem right because it's in free fall though.
P=mv ≈ 415
415/0.4=1037.5N?

Is this right?
 
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Crushgear64 said:

Homework Statement



A 40kg branch falls 5.5m and lands on a roof. The roof withstood the the impact.

Homework Equations



If the impact time was 0.4 second calculate the magnitude of the average force exerted on the roof during the impact.

The Attempt at a Solution



F=ma doesn't seem right because it's in free fall though.
P=mv ≈ 415
415/0.4=1037.5N?

Is this right?
That is correct !
 
Thread 'Correct statement about size of wire to produce larger extension'

Thread 'Correct statement about size of wire to produce larger extension'

The answer is (B) but I don't really understand why. Based on formula of Young Modulus: $$x=\frac{FL}{AE}$$ The second wire made of the same material so it means they have same Young Modulus. Larger extension means larger value of ##x## so to get larger value of ##x## we can increase ##F## and ##L## and decrease ##A## I am not sure whether there is change in ##F## for first and second wire so I will just assume ##F## does not change. It leaves (B) and (C) as possible options so why is (C)...
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