1) one end of a short aluminum rod is in a campfire and the other end is in a bl
ID: 1267838 • Letter: 1
Question
1) one end of a short aluminum rod is in a campfire and the other end is in a block of ice. If 100 J of energy are transferred from the fire to the rod, and if the temperature at every point in the rod has reached a steady value, how much energy goes from the rod into the fire?
2) two blocks of copper, one with a mass of 1 kg and the other with a mass of 3 kg are at the same temperature. which block has more thermal energy? if the blocks are placed in thermal contact, will the thermal energy of the blocks change? if so how?
Explanation / Answer
1) Heat energy from fire to alluminium = 100J
The amount of energy that goes from rod to fire = - ( Heat energy from fire to alluminium ) = -100J
2)3kg block has more thermal energy.
No,if the blocks are placed in thermal contact, thermal energy of the blocks do not changes. It is because because for thermal energy change to take place, there must be a temperature difference.
EXPLANATION -
suppose 1kg block and 3 kg gets its temperature raised by 100K but as 3kg has more mass,hence amount of thermal energy required to cause this much temperature change is more as Q=m* s * (Tf - To)
Q is proportional to mass and mass of 3kg is more than 1 kg, so more thermal energy in 3 kg block than 1 kg block.
But as both have reached the same final temperature,they cannot exchange energy with each other because heat transfer will occur only when there exist temperature difference between bodies.
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