Some students carry out investigations with an electric motor - Edexcel - GCSE Physics - Question 1 - 2012 - Paper 1
Question 1
Some students carry out investigations with an electric motor.
(a) Complete the sentence by putting a cross (X) in the box next to your answer.
The students read t... show full transcript
Worked Solution & Example Answer:Some students carry out investigations with an electric motor - Edexcel - GCSE Physics - Question 1 - 2012 - Paper 1
Step 1
Complete the sentence by putting a cross (X) in the box next to your answer.
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Answer
The statement best describes the idea of D conservation of energy, as it indicates that energy is neither created nor destroyed but is transformed into other forms.
Step 2
Calculate the input power to the motor. State the unit.
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Answer
The input power (P) can be calculated using the formula:
P=VimesI
Where V is the voltage (6 V) and I is the current (0.5 A).
Thus,
P=6extVimes0.5extA=3extW
The input power to the motor is 3 Watts.
Step 3
How much energy is wasted?
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Answer
To calculate the wasted energy, subtract the energy transferred to the weight from the input energy:
extWastedEnergy=extInputEnergy−extEnergyTransferred
Substituting the values:
extWastedEnergy=200extJ−50extJ=150extJ
Thus, the energy wasted is 150 J.
Step 4
Calculate the efficiency of the motor.
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Answer
Efficiency can be calculated using the formula:
ext{Efficiency} = rac{ ext{Useful Energy Output}}{ ext{Total Energy Input}} imes 100
Substituting the values:
ext{Efficiency} = rac{50 ext{ J}}{200 ext{ J}} imes 100 = 25\%
Thus, the efficiency of the motor is 25%.
