Could anyone good at mechanical principles answer this thanks ?

[stacychloe]

a pile driver has a mass of 100kg and falls 3m onto the pile which has a mass of 200kg. The two become joined on impact. The pile is driven into the ground a distance of 0.08 m each time. The mass is raised by a winch between each impact. The graph in the lnk below shows how the velocity of the driver varies with time as it is raised by the winch.

http://cid-abcca0c046a77097.skydrive.live.com/ self.aspx/graph/graph.bmp

[Rollo]

Is there a question here?

[stacychloe]

sorry

calculate
1)the initial potential energy of the driver before it is dropped.

2)the velocity of the driver just before impact.

3)the velocity of the pile and the driver immediately after impact.

4) the deceleration of the pile and thhe driver immediately after impact.

5) the average ground resistance.

4)the work done driving the pile into the ground.

[jake-the-peg]

1)well that's just mgh (mass times g times Height) isn't it - I'll guess you got that

2) Newtons laws of motion V�=U�+2aS
U is 0 a is g (acceleration due to gravity)
S is 3m - mix it all around and get V

3) conservation of momentum
Momentum of weight= momentum of weight and pile combined

MV=(m+M)V'

You've got V from 2 M=100Kg M+m = 300Kg V' should be easy.

4) Newtons laws of motion again
V�=U�+2aS

This time we want a, S is the distance driven in and we have U, the intial velocity, V the final velocity is of course 0

5) Ground resistance F=ma
here a is the deceleration, m is the combined mass

6) Work is force times distance, you've worked out the Force and you have the distance

Don't quite know why they gave you the graph