Identical detectors at equal distances from two heated plates record infrared signal after the background reading has been subtracted. Both plates have the same area and temperature. Matt black gives 8.4 units and shiny silver gives 2.1 units.
.1
Calculate how many times larger the black-plate signal is.
[2 marks]
.2
Evaluate whether the measurements support using a shiny surface to reduce thermal radiation losses.
[3 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A coastal community chooses between offshore wind and a tidal barrage. Wind is variable. The times of tides are predictable, but the barrage produces little electricity around high and low tide. The estuary is a habitat for migratory birds.
Compare the reliability and environmental effects of the two choices.
[4 marks]
6 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A detector registers 96 counts per minute of background radiation. With a source present it registers 896 counts per minute initially and 496 counts per minute after 12 minutes.
.1
Calculate the initial corrected detected count rate in min−1 (counts per minute).
[2 marks]
.2
Determine the half-life in minutes.
[2 marks]
.3
Explain why the background must be subtracted before comparing the rates.
[2 marks]
5 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A car has thinking distance 10 m and braking distance 18 m on a dry road. On a wet road at the same initial speed, its thinking distance is still 10 m and braking distance is 30 m.
.1
Calculate the percentage increase in total stopping distance on the wet road.
[3 marks]
.2
Explain why wet conditions increase braking distance in this comparison.
[2 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A vibrating string is observed with a ruler in its plane. Its equilibrium position is at 12.0 cm on the ruler. The highest and lowest positions are 14.4 cm and 9.6 cm.
.1
Calculate the amplitude in metres.
[2 marks]
.2
A pupil says that increasing amplitude necessarily increases frequency. Evaluate the claim.
