A wire carries 4.0 A perpendicular to a 0.20 T magnetic field. The length in the field is 0.10 m. In a second test both the current and the field direction are reversed, but their magnitudes are unchanged.
.1
Calculate the magnetic force magnitude in the second test.
[2 marks]
.2
Explain whether the force direction changes in the second test.
[2 marks]
5 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A ball is falling through air. At one instant its weight is 7.0 N downwards and air resistance is 2.5 N upwards. Only these two forces act.
.1
Calculate the magnitude of the resultant force.
[2 marks]
.2
Compare the two forces as contact or non-contact forces and state the resultant direction.
[3 marks]
5 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
In a collision test the total momentum before impact is 0.500 kg m/s. Three repeats give total momentum after impact of 0.492, 0.501 and 0.495 kg m/s, all in the original direction.
.1
Calculate the mean total momentum after impact.
[2 marks]
.2
The uncertainty in the mean is estimated as 0.010 kg m/s. Evaluate whether these results contradict conservation of momentum.
[3 marks]
6 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
At fixed potential difference 3.0 V, a thermistor carries 0.0020 A in cool water and 0.0060 A in warm water. It is the type whose resistance falls as temperature rises.
.1
Calculate the resistance in cool water.
[2 marks]
.2
Calculate the resistance in warm water.
[2 marks]
.3
A pupil says the current tripled because the supply voltage tripled. Evaluate the statement using the data.
[2 marks]
5 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A pure liquid cools at a steady rate of energy loss. Its temperature falls from 60 °C to 40 °C in 4 minutes, stays at 40 °C for 6 minutes, then falls below 40 °C.
024681012203040506070Time (min)Temperature (°C)
.1
Calculate the average rate of temperature decrease during the first 4 minutes, in °C per minute.
[2 marks]
.2
Explain the horizontal section and the fall afterwards on the temperature-time graph.
