Respuesta :
Answer:
Case 1
Explanation:
Given :Identical balls are dropped from the same initial height and bounce back to half the initial height
In case 1 where the the ball bounces off a cement floor, because in this case the time of contact will be less( as compared with time of contact with the stretchy rubber) And hence, a greater force will be felt by the ball ( actually impulse will be more).
impulse I= ΔF/Δt
ΔF= change in force and Δt =change in time
The average force acting on case 1 (cement floor) will be the greatest because of short time of contact.
The average force experienced in each case is given by Newton's second law of motion;
[tex]F = ma = \frac{m(v_2 - v_1)}{t}[/tex]
where;
- m is the mass of the object
- v₁ and v₂ are the initial and final velocity respectively.
- t is the time of impact
The magnitude of the force is inversely proportional to the time of impact of the object.
In case 1:
- the cement floor is a hard surface and the time spent by the ball before bouncing off will be short.
In case 2:
- the stretchy rubber is elastic and the time spent by the ball before bouncing off will be greater compared to the cement.
Thus, the average force acting on case 1 (cement floor) will be the greatest because of short time of contact.
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