EnergyIB MYP Physics: Topic test

20 questions, 54 marks

IB MYP Physics

Energy topic test

Total 54 marks

Name

Class

Date

1
A child in Seoul winds up the spring of a clockwork toy car, puts the car on the floor and lets it go. The car moves across the floor and slowly stops.
(a)
In which energy store is the energy kept while the child holds the wound-up car?
[1 mark]
AKinetic
BChemical
CElastic potential
DGravitational potential
(b)
What has happened to the kinetic energy of the car when it has stopped?
[1 mark]
AIt has been transferred to thermal energy in the floor and surroundings
BIt has been destroyed
CIt has been transferred back to the elastic store of the spring
DIt has been transferred to the kinetic store of the floor
(c)
Describe how energy is transferred to the spring when the child winds it.
[2 marks]
Total for question 1: 4 marks
2
An electric kettle in a flat in Sydney takes in 300 000 J of electrical energy to boil some water. Of this, 255 000 J is transferred to the thermal energy of the water.
(a)
What is the efficiency of the kettle?
[1 mark]
A15%
B85%
C0.85%
D118%
(b)
A manufacturer claims that the kettle is 120% efficient. Why can this claim not be true?
[1 mark]
AKettles waste no energy
BEfficiency is always exactly 100%
CSome energy is always destroyed
DA device cannot give out more useful energy than it takes in, because energy cannot be created
(c)
Suggest one way to make the kettle more efficient, and explain why it works.
[2 marks]
Total for question 2: 4 marks
3
A diver of mass 60 kg stands on a platform 10 m above the surface of a pool in Acapulco, Mexico. She steps off and falls from rest. Ignore air resistance and take g = 10 N/kg.
(a)
Calculate the gravitational potential energy that she loses as she falls to the surface of the water.
[3 marks]
(b)
Calculate her speed as she reaches the water.
[4 marks]
Total for question 3: 7 marks
4
A government in a sunny desert country wants to supply electricity to a new city of 500 000 people, who need power by day and by night. It is choosing between a large solar farm and a gas-fired power station. The solar farm releases no carbon dioxide while it runs and has low running costs. The gas power station can be switched on at any time and releases carbon dioxide when it burns gas.
(a)
Discuss whether the government should build the solar farm or the gas-fired power station.
[6 marks]
(b)
Explain how burning gas for electricity contributes to the enhanced greenhouse effect, and describe two possible consequences.
[6 marks]
Total for question 4: 12 marks
5
A weightlifter in Tbilisi, Georgia, lifts a barbell weighing 1500 N from the floor to a height of 2.0 m in 4.0 s.
(a)
How much work does he do on the barbell?
[1 mark]
A3000 J
B750 J
C6000 J
D1500 J
(b)
What is the power developed by the weightlifter?
[1 mark]
A12 000 W
B3000 W
C1500 W
D750 W
(c)
Another weightlifter lifts the same barbell through the same height in 2.0 s. State whether his power is greater, the same or smaller, and give a reason.
[2 marks]
Total for question 5: 4 marks
6
A petrol engine in a car in Johannesburg takes in 100 kJ of energy from the petrol each second. It transfers 25 kJ each second to the car as useful kinetic energy. The rest is wasted: 65 kJ each second as thermal energy in the exhaust and engine, and 10 kJ each second as sound.
(a)
In which energy store is the energy before the petrol is burned?
[1 mark]
AThermal
BChemical
CKinetic
DElastic
(b)
What happens to the wasted energy?
[1 mark]
AIt is destroyed
BIt is stored by the engine for later use
CIt spreads out into the surroundings, mainly as thermal energy, and is hard to use again
DIt is transferred back to the petrol
(c)
Calculate the efficiency of the engine.
[2 marks]
Total for question 6: 4 marks
7
A wind farm in western Scotland has 20 identical turbines. When the wind is strong enough, each turbine has a power output of 3.0 MW.
(a)
Calculate the total power output of the wind farm, in MW and in W.
[3 marks]
(b)
Calculate the energy transferred by the wind farm in 30 s when all the turbines are working at full power. Give your answer in MJ.
[4 marks]
Total for question 7: 7 marks
8
A student in Dublin releases a 0.50 kg trolley from rest on a smooth ramp and measures its speed at the bottom with a light gate. She predicts that doubling the release height will double the speed at the bottom. For release heights of 0.10 m, 0.20 m and 0.30 m, she measures speeds of 1.3 m/s, 1.8 m/s and 2.2 m/s. Take g = 10 N/kg.
(a)
For the 0.20 m release, calculate the gravitational potential energy lost and the kinetic energy gained. Use your answers to explain why they are not equal.
[6 marks]
(b)
Evaluate the student's prediction using the data, and suggest one improvement to her investigation.
[6 marks]
Total for question 8: 12 marks

End of questions

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).