A 2.12-kg copper block is given an initial speed of 5.41 m/s on a rough horizont
ID: 1549841 • Letter: A
Question
A 2.12-kg copper block is given an initial speed of 5.41 m/s on a rough horizontal surface. Because of friction, the block finally comes to rest. (a) If the block absorbs 85.0% of its initial kinetic energy as internal energy, calculate its increase in temperature. °C (b) What happens to the remaining energy? 1) It is absorbed by the horizontal surface on which the block slides. 2) It vanishes from the universe. 3) It becomes chemical energy. 4) It is so minute that it doesn't factor into the equation. 5) It becomes potential energy.
Explanation / Answer
energy released E = change in KE = (1/2)*m*v^2
energy absorbed = 0.8*E
heat absorbed = m*S*dt = 0.85*E
S*dt = 0.85*(1/2)*v^2
386*dt = 0.85*(1/2)*5.41^2
dt = 0.032 0C
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It is absorbed by the horizontal surface on which the block slides
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