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Matter In Our Surroundings

Question
CBSEENSC9006354

Suppose a hammer which falls freely on a nail placed on a piece of wood has a mass of 1 kg. If it falls from a height of 1 m, how much kinetic energy will it have just before hitting the nail ?

(Take value of g = 10 m/s2.)

Solution

Given comma

Initial space velocity comma space straight u space equals space 0 space straight m divided by straight s

Mass comma space space straight m space equals space 1 space kg

Distance comma space straight s space equals space 1 space straight m

Acceleration space due space to space gravity comma space straight g space equals space 10 space straight m divided by straight s squared

Using space the space 3 to the power of rd space equation space of space motion comma space

space space space space space space space space straight v squared minus straight u squared space equals space 2 gs space space space space space

therefore space space space space straight v squared minus 0 squared space equals space 2 space cross times space 10 space cross times space 1

rightwards double arrow space space space space space space space space straight v space equals square root of 20 space straight m divided by straight s
That space is comma space
space straight K. straight E. space space equals 1 half mv squared space space
space space space space space space space space space space space space equals space 1 half cross times 1 space cross times space open parentheses square root of 20 close parentheses squared
space space space space space space space space space space space space equals space 10 space straight J.