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To find momentums we need the speeds before and after collision. The simplest way to find these speeds is to use the energy conservation law.

Before fall, a ball had only potential energy `mgh_1.` Just before collision it had only kinetic energy m `V_1^2/2,` and they was equal. Therefore `V_1=sqrt(2gh_1),` where `h_1=3m.`

The same consideration gives that the speed after the collision is `V_2=sqrt(2gh_2),` where `h2=2m.` Now we can answer (i) and (iii).

(i) the momentum before collision is `mV_1 approx 0.61(m/s),` after is `mV_2 approx 0.50(m/s).`

(iii) note that impulse is a vector, it has the same direction as velocity. The momentum before collision is directed downwards and after -- upwards. So the difference of moments is the sum of their magnitudes, i.e. 1.11m/s.

For (ii) we have to know that a force may be expressed as the derivative of a momentum (Newton's Second law, actually). Therefore the integral of force is the difference of momentums. And the average force is this difference divided by a time. Force is upwards all the time.

(ii) average force is `1.11/(5*10^(-3)) approx 222(N).`

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