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2 years ago

8

A sledge hammer has a mass of 4.0 kg and is moving at a speed of 6.0m/s when it strikes a fence post, driving it 10 cm further i

nto the ground.
A) what was the kinetic energy of the sledge hammer?
B) what is the average force exerted on the fence post by the hammer?

1 answer:

Afina-wow [57]2 years ago

8 0

Part a)

kinetic energy of the hammer will be

$KE = \frac{1}{2} mv^2$

here we know that

m = 4 kg

v = 6 m/s

now by the equation of kinetic energy we have

$KE = \frac{1}{2}*4 * 6*6$

$KE = 72 J$

Part b)

for finding the force we will have

$v_f^2 - v_i^2 = 2 a d$

here we know that

$v_f = 0$

$v_i = 6 m/s$

$d = 10 cm = 0.10 m$

now from above equation we have

$0 - 6^2 = 2 * a * 0.10$

$a = -180 m/s^2$

now by Newton's II law we have

$F = ma$

$F = 4*180 = 720 N$

so it requires 720 N.

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2 years ago

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6 0

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