Efficiency of a motor
* Required
A student investigated the efficiency of a motor using the equipment shown below:
Key points:
The motor is used to lift a weight of 2.5N a height of 2.0m
He measured the speed at which the weight was lifted and calculated the efficiency of the energy transfer.
He repeated the experiment to gain two sets of data.
The student ensure that the height lifted is the same each time. What type of variable is this?
*
1 point
Independant variable
Dependant variable
Control variable
Why does the student repeat the experiment? (Tick all that apply)
*
1 point
So that they can calculate a mean
So that they can identify anomalies (outliers)
So that the results are accurate
To reduce the effect of random errors.
Required
The results from the experiment are shown in the graph:
Which two of the following are conclusions that could be drawn from the graph above.
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1 point
As the speed increases, the efficiency increases
As the speed increases, the efficiency decreases
The efficiency will keep increasing so long as the speed increases.
The efficiency tends towards a constant value at higher speeds
What is the main cause of waste energy from the motor?
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1 point
The kinetic energy of the motor
The sound emitted by the motor
The heat transferred to the surrondings
When the total input to the motor is 5W, it is not possible to lift the 2.5N weight. What is the efficiency of the motor in this situation?
1 point
0%
It is not possible to tell with this information.
100%
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