Can power be negative in physics? I am doing a lab in which I run down the stairs as quickly as possible. They are 5.4m tall and
1 answer:
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a) , 1.6 A
b) , 1.33 A
Explanation:
a)
In this situation, we have two resistors connected in series.
The equivalent resistance of resistors in series is equal to the sum of the individual resistances, so in this circuit:
where
Therefore, the equivalent resistance is
Now we can use Ohm's Law to find the current flowing through the circuit:
where
V = 8 V is the voltage supplied by the battery
is the equivalent resistance of the circuit
Substituting,
The two resistors are connected in series, therefore the current flowing through each resistor is the same, 1.6 A.
b)
In this part, a third resistor is added in series to the circuit; so the new equivalent resistance of the circuit is
where:
Substituting, we find the equivalent resistance:
Now we can find the current through the circuit by using again Ohm's Law:
where
V = 8 V is the voltage supplied by the battery
is the equivalent resistance
Substituting,
And the three resistors are connected in series, therefore the current flowing through each resistor is the same, 1.33 A.
Efficiency of heat engine is determined by the ratio of difference in temperature of cold from hot reservoir to the temperature of hot reservoir over temperature of hot reservoir.
Answer: Option A
<u>Explanation:</u>
Efficiency is defined as the output from the input. So it is the ratio of energy output to the energy input. In case of temperature, it is the change in temperature from hot reservoir to cold reservoir with the overall hot reservoir temperature.
Thus, option A is the most suitable as the heat will be transferred from high temperature to low temperature. So the hot reservoir will be releasing the energy. So the conversion of hot reservoir temperature to cool reservoir temperature is defined as the efficiency. Thus, option A is the most suitable.