All it does is lets him pull in a more convenient direction to raise the load. It has no effect on the required force.
V^2=u^2 +2aS
U is found first by considering that first 8 secs and using v=u+at. {different v and u though}
V=-u+gt.
Magnitude of u = magnitude of v if there is no resistance ( because the conservation of energy says the k. E. must be the same when it passes you as when it left your hand).... up is negative here, down is positive.
V+v=gt
2v= g x 8
V=4xg.= the initial velocity for the next calculation
V^2=(4g)^2+(2xgx21)
So v can be calculated.
The density of an object can be calculated using the formula Density = Mass/Volume. In this case however we are searching for the volume and must rearrange the formula so that we are solving for the volume. If you multiply both sides by volume and then divide both sides by mass you end up with the equation Volume = Mass/Density.
Volume = 1500g/1.5g/cm^3
Volume = 1000 cm^3
Its the first one, second one, and last one.
Lets do
We know
The rate of change of velocity is acceleration .


Integrate both sides

As acceleration is constant .Take it outside of integral .On velocity we can take limit u to v and time from 0 to t

Hence


