Problem (possibly) involving Springs, Free Fall and Air Resistance

AI Thread Summary
The discussion revolves around a physics problem involving a mass dropped from a height H, which rebounds with the same speed after hitting a surface while experiencing air resistance. Participants are trying to determine the mass's speed just before the first impact, the height it reaches after rebounding, and the total distance traveled before coming to rest. There is confusion about how to incorporate the air resistance force into the equations of motion, particularly in relation to potential and kinetic energy. The net acceleration during free fall and the effects of air resistance on subsequent bounces are also key points of consideration. Overall, the problem requires careful application of physics principles to account for energy transformations and forces acting on the mass.
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Homework Statement


A mass m is dropped from a height H onto a hard, flat surface. When it collides with the surface, it rebounds with the same speed it had before the collision. However, there is a constant force of air resistance f acting on the mass as it undergoes this motion. Answer the following in terms of f, m, H, and g.

a) How fast is the mass moving just before it hits for the first time?
b) How high does the mass go after the first collision?
c) After how many bounces, the ball comes to rest on the surface. While its overall displacement was -H, it traveled a considerably larger distance. Determine the total distance traveled by the ball.


Homework Equations


F=-kx
PEsp=1/2kx^2
KEi+PEi-f(friction)=KEf+PEf+PEsp


The Attempt at a Solution


Should I look at this problem as if the ground were a spring? If so, how do I determine k and x for the equation? It doesn't necessarily travel any distance (for the x variable)

a) Would I simply use PEi=KEf? Should I assume that the mass starts from rest? Or should I put in PEi+KEi=KEf.

b)If I were to assume that it was a spring, how would I translate k and x into other variables to fit with the specifications of the equation (using f, m, H and g) If not, I have no idea where to even begin. Would I simply use the previously found final velocity from a and use that as my new initial, then calculate friction and find the distance?

c) Would I use the final velocity before hitting the ground of the second bounce to calculate the initial velocity for the third bounce, and so on? I have no idea where to even begin to solve this part of the problem. Any hints or suggestions would be greatly appreciated.
 
Physics news on Phys.org
When mass is moving down, the net acceleration is (g - f/m), where f is the air resistance which opposes the free fall.
While coming down, the net retardation is ( g + f/m)
 
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