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
A manufacturer claims a rubber luggage strap is more suitable than a steel spring for repeated stretching under load. A fair comparison must use the same maximum applied force and check whether each sample returns to its original length.
Plan an investigation to compare how extension depends on force for the strap and spring, and test whether they recover their original lengths after repeated loading.
[6 marks]
6 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
Students want to compare wave speeds on the same stretched string at two different tensions. They have a vibration generator, signal generator, pulley, masses, metre rule, a high-speed camera with a short exposure and an absorbing termination that suppresses reflected waves before the pulley. The camera resolves individual travelling-wave crests.
Plan a valid comparison using measurements of frequency and wavelength.
[6 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A light pulse and a sound pulse leave the same device simultaneously. The observer is 680 m away. Take sound speed as 340 m/s and light speed as 3.0×108 m/s.
.1
Calculate the travel time of the sound.
[2 marks]
.2
Explain why timing from the visible flash to the sound is a reasonable way to measure the sound travel time here.
[2 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.
