Work done by the hammer in a single stroke?

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The discussion revolves around calculating the work done by a hammer in driving a 9-inch nail into a log. The energy of the hammer before striking the nail is calculated to be 100J, based on its mass and height. After accounting for a 20% energy loss during the collision, 80J is delivered to the nail. There is confusion regarding whether the work done should also be considered as 100J, and the participant is uncertain about how far the nail is driven into the log. The thread seeks clarification on these calculations and assumptions.
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Need some verification.

I am trying to drive a 9 inch nail into a log with a 10kg hammer, raising it to a maximum height of 1m and then gain momentum as it is swung down.

a. Energy of the hammer immediately prior to striking the nail:
10kg\times10\frac{m}{s^2}\times1m = 100J.

b. If 20% of hammer's energy is dissipated during the collision, how much energy is delivered to the nail in a single stroke provided the hammer remains at rest after hitting the nail?

80\%\times100J = 80J.

c. Work done by the hammer in a single stroke?

Shouldn't this be the 100J also?

d. How far into the log is the nail driven in a single stroke?

Not sure about this one!

Could someone please give me some hints on these. Thanks.
 
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Did you state all the information you were given for this problem? It seems that some assumption is being made that I am not seeing, and since nobody else has replied I assume others are not seeing it either.
 

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