A student says: "A stationary pair of magnets pushes apart, so momentum has been created. Two carts then collide and stick together, so momentum is destroyed." Both events occur on horizontal low-friction tracks.
Evaluate these two claims using momentum and energy, stating the system you consider.
[6 marks]
5 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
An imaging leaflet gives typical effective doses: one chest X-ray 0.020 mSv and one CT examination 4.0 mSv. These values are supplied; you do not need to recall dose units.
.1
Calculate the number of chest X-rays giving the same listed total dose as one CT examination.
[2 marks]
.2
Explain why the dose comparison alone cannot decide whether a patient should have the CT examination.
[3 marks]
6 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
Two lamps provide the same useful light power of 9.0 W. Lamp A takes 60 W electrically; lamp B takes 12 W. Both are used for 300 s.
.1
Calculate the efficiency of lamp B as a percentage.
[2 marks]
.2
Calculate how much less energy lamp B takes from the supply in 300 s.
[2 marks]
.3
Explain why the smaller input does not make lamp B dimmer in this comparison.
[2 marks]
6 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
A simple motor has a rectangular current-carrying coil between two magnet poles. A student suggests increasing current, using stronger magnets and making the active sides parallel to the magnetic field to increase rotation.
Evaluate these suggestions using the motor effect. Explain the role of the two sides of the coil.
[6 marks]
6 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
A lifting device measures the weight of several masses on a planet. Results are 6 N for 2 kg, 15 N for 5 kg and 24 N for 8 kg. Measurements pass through the origin on a weight-mass graph.
01234567891051015202530Mass (kg)Weight (N)
.1
Calculate the gravitational field strength on the planet.
[2 marks]
.2
Calculate the mass of an object that weighs 42 N there.
[2 marks]
.3
Explain why using several masses supports the result more than using one reading.
