Hospitals use X-rays to form images of the inside of the body. A CT scan uses X-rays from many directions. The table shows some typical radiation doses.
Typical radiation dose in millisieverts: one chest X-ray 0.02; one CT scan of the chest 7.0; background radiation in one year, UK average, 2.7.
Source of radiation
Typical dose in mSv
One chest X-ray
0.02
One CT scan of the chest
7.0
Background radiation in one year (UK average)
2.7
.1
Calculate how many chest X-rays give the same dose as one CT scan of the chest.
[2 marks]
.2
Calculate the dose from one CT scan of the chest as a percentage of the yearly background dose.
[2 marks]
.3
A patient has had a cough for several months. Evaluate the use of a CT scan of the chest to find the cause.
[3 marks]
.4
Give one harmful effect of ultraviolet radiation on the human body.
[1 mark]
7 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A skydiver of mass 75 kg jumps from a plane.
Gravitational field strength = 9.8 N/kg.
.1
At one moment the air resistance on the skydiver is 285 N. Calculate the acceleration of the skydiver at this moment.
[3 marks]
.2
Explain why the skydiver reaches a terminal velocity.
[4 marks]
7 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
Waves travel across a pond. A floating leaf moves up and down 5 times in 2.0 s. The distance between neighbouring crests is 0.40 m.
.1
Calculate the frequency of the waves.
[1 mark]
.2
Calculate the speed of the waves.
[2 marks]
.3
Calculate the period of the waves.
[2 marks]
.4
The leaf moves up and down but does not travel across the pond with the waves.
Explain what this shows about the waves.
[2 marks]
5 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
The diagram shows the horizontal forces on a car.
car3000 N driving force1800 N air resistance400 N friction
.1
Calculate the resultant force on the car.
[2 marks]
.2
Describe the effect of this resultant force on the motion of the car.
[1 mark]
.3
Air resistance is a contact force. Gravity is a non-contact force. Explain the difference.
[2 marks]
7 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A student holds a steel paperclip near a bar magnet.
.1
Explain the difference between a permanent magnet and an induced magnet.
[2 marks]
.2
The paperclip is attracted to the north pole and also to the south pole of the magnet. Explain why.
[2 marks]
.3
Describe how the strength of the magnetic field changes as you move further from the magnet.
[1 mark]
.4
With no magnets nearby, a compass needle still points north. Explain what this shows about the Earth.
