A stone is dropped from from rest at the top of a mine shaft. It takes 95 seconds for the stone to fall to the bottom of the min
1 answer:
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1) Assuming an adult person has an average mass of m=80 kg, and assuming it takes about 30 seconds to climb 5 meters of stairs, the energy used by the person is
So the power output is
And since the estimate we made is very rough, we can say that the power output of the person is comparable to the power output of the light bulb of 100 W.
2) Based on the results we found in the previous part of the exercise, since the power output of the person is comparable to the power output of 1 light bulb of 100 W, we can say that the person could have kept burning only one 100-W light bulb during the climb.
So the power output is
And since the estimate we made is very rough, we can say that the power output of the person is comparable to the power output of the light bulb of 100 W.
2) Based on the results we found in the previous part of the exercise, since the power output of the person is comparable to the power output of 1 light bulb of 100 W, we can say that the person could have kept burning only one 100-W light bulb during the climb.
Answer : The temperature when the water and pan reach thermal equilibrium short time later is,
Explanation :
In this problem we assumed that heat given by the hot body is equal to the heat taken by the cold body.
where,
= specific heat of aluminium =
= specific heat of water =
= mass of aluminum = 0.500 kg = 500 g
= mass of water = 0.250 kg = 250 g
= final temperature of mixture = ?
= initial temperature of aluminum =
= initial temperature of water =
Now put all the given values in the above formula, we get:
Therefore, the temperature when the water and pan reach thermal equilibrium short time later is,