Mark Scheme

Section A: 1. C; 2. C; 3. B; 4. B; 5. B. (5)

6 (a) scalar has magnitude only (1); vector has magnitude and direction (1). (b) W = mg = 1200 × 9.8 = 11 760 N (1 method, 1 answer). (c) a = Δv ÷ t = 18 ÷ 6 = 3 m/s² (1 method, 1 answer). (d) as it falls, air resistance increases with speed (1); until air resistance equals weight (1); resultant force is zero so it falls at constant maximum speed (1). (9)

7 (a) thinking distance + braking distance (1). (b) any two: tiredness; alcohol/drugs; distractions; higher speed (2). (c) less friction/grip between tyres and road (1); so the car travels further while braking (1). (d) kinetic energy is transferred to thermal energy in the brakes (1) which heat up (1). (6)

8 (a) force is directly proportional to extension (1) up to the limit of proportionality (1). (b) k = F ÷ e = 8 ÷ 0.04 = 200 N/m (1 method, 1 answer). (4)

9 (a) distance between two corresponding points on adjacent waves (1). (b) v = fλ = 50 × 6 = 300 m/s (1 method, 1 answer). (c) transverse: oscillations perpendicular to energy transfer; longitudinal: oscillations parallel (1+1). (d) any two correct use+region: e.g. radio – broadcasting; microwaves – satellite/cooking; infrared – heating/remote controls; X-rays – medical imaging (2). (7)

10 (a) permanent magnet produces its own field all the time (1); induced magnet is only magnetic in a field and loses it when removed (1). (b) field lines from north to south (1); strongest at the poles (where lines are closest) (1). (c) any two: more current; more turns on the coil; add an iron core (2). (6)

11 — Levels (6): Indicative: a current-carrying conductor in a magnetic field experiences a force because the wire's field interacts with the magnet's field. The force is greatest when the wire is at 90° to the field and zero when parallel. Reversing the current or the field reverses the force. The size increases with a larger current or stronger field (F = BIL). Used in electric motors / loudspeakers.

• L3 (5–6): Explains the effect, how size and direction change, and names a device.
• L2 (3–4): Some explanation with one or two factors.
• L1 (1–2): Simple statements.

Sample Answers with Examiner Commentary

Question 11 — Sample Answers

Grade 9 answer "When a current-carrying wire is placed in a magnetic field, the magnetic field produced by the current interacts with the field of the magnet, and the wire experiences a force — this is the motor effect. The force is greatest when the wire is at 90° to the field and zero when it is parallel to the field. The direction of the force can be reversed by reversing either the current or the magnetic field, and is found using Fleming's left-hand rule. The size of the force increases if the current is increased or a stronger magnet is used. The motor effect is used in electric motors and loudspeakers." Mark: 6/6. Examiner commentary: Explains the cause, both how the size and the direction change, and names a device. Uses Fleming's left-hand rule correctly. Top band.

Grade 6 answer "A wire with a current in a magnetic field feels a force. If you reverse the current the force goes the other way. A bigger current gives a bigger force. This is used in motors." Mark: 4/6. Examiner commentary: Correct on the effect, reversing direction, increasing size and a device, but does not mention that the force is greatest at 90° to the field, nor Fleming's left-hand rule. Either would reach the top band.

Question 6(d) — Sample Answers

Grade 9 answer "As an object falls it speeds up, and air resistance increases with speed. Eventually the air resistance becomes equal to the object's weight, so the resultant force is zero. With no resultant force there is no acceleration, so the object falls at a constant maximum speed called the terminal velocity." Mark: 3/3. Examiner commentary: All three points — air resistance increasing with speed, balancing weight, and constant speed at zero resultant force.

Grade 6 answer "It is the fastest speed a falling object reaches when air resistance equals weight so it stops accelerating." Mark: 2/3. Examiner commentary: Credit for air resistance equalling weight and no further acceleration, but it does not state that air resistance increases as the object speeds up, the point that explains why the forces come into balance.