- #1

notsoclever

- 8

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## Homework Statement

A pole with mass m

_{2}= 2 Kg is planted on the ground with a consecutive hammer hits. The hammer ha a mass m

_{1}= 4 kg and is dropped from 1 meter upon the pole. With a single hit the pole penetrate the ground of 2 cm.

Find:

a) the total resistence R to the penetration, supposing constant that R is costant for each hit and the collision is perfectly inelastic.

b)The dissipation of energy after the collision

## Homework Equations

Momentutm

Conservation of energy

## The Attempt at a Solution

I've found the velocity of the hammer just before the collision using the conservation of energy, that is 4.4 m/s.

Using the momentum consrvation and knowing that it is an perfectly inelastic collision I've found that the velocity of the sistem after the hammer hit is 2.9 m/s.

I think till now there is anything to say (If I made any mistakes please tell me).

After that I've though to find the acceleration of the pole knowing that the penetration is 0.02 meters and that the final velocity is 0, using this formula [tex]a=(V_0)^2/2S[/tex] where [tex]V_0 = 2.9[/tex].

Knowing that the [tex]F=ma[/tex] I've thougt to find the resistance R but the result is wrong.

Can you help me please? (The result of R should be 84.9 N)