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moenste
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Homework Statement
A bullet of mass 2.0 * 10-3 kg is fired horizontally into a free-standing block of wood of mass 4.98 * 10-1 kg, which it knocks forward with an initial speed of 1.2 m s-1.
(a) Estimate the speed of the bullet.
(b) How much kinetic energy is lost in the impact?
(c) What becomes of the lost kinetic energy?
Answers:
(a) 300 m s-1;
(b) 89.64 J.
Homework Equations
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The Attempt at a Solution
(a) 2.0 * 10-3 kg * X m s-1 = 4.98 * 10-1 kg * 1.2 m s-1
X = 298.8 m s-1
(b) Kinetic energy = 1/2 * m * v2 = 0.5 * (2.0 * 10-3) * 298.8 m s-1 = 89.28 J.
(c) Kinetic energy lost is potential energy gained.
However, as the answers don't fit the book answers 100% and I have no answer for the (c) part, I am not sure whether I am right or wrong. Any help please? Thanks in advance for any tips.