Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic P1.1 — Physical quantities and measurement techniques (Part (a)(i))
• Topic P1.2 — Motion (Parts (a)(ii) & (b))
• Topic P1.3 — Mass and weight (Part (c)(i))
• Topic P1.6.2 — Work / Kinetic energy (Part (c)(ii))
(a)(i) Vector quantities: gravitational field strength, weight.
Vector quantities have both magnitude and direction. Gravitational field strength and weight are vectors; energy, temperature, and time are scalars (magnitude only).
(a)(ii) Velocity is speed in a given direction.
Velocity is a vector quantity that describes the rate of change of displacement (distance travelled per unit time in a specific direction).
(b) Acceleration = 0.45 m/s².
Acceleration is the gradient of a speed-time graph. During the first 12 seconds, the speed increases from 0 to 5.4 m/s.
\(a = \frac{\Delta v}{\Delta t} = \frac{5.4 – 0}{12 – 0} = \frac{5.4}{12} = 0.45\text{ m/s}^2\)
(c)(i) Ratio = 3.6 (or –3.6).
\(\text{ratio} = \frac{35}{9.8} = 3.57 \approx 3.6\)
(The negative sign indicates deceleration/opposite direction.)
(c)(ii) Mass = 1200 kg.
\(E_k = \frac{1}{2}mv^2\)
\(470000 = \frac{1}{2} \times m \times 28^2\)
\(470000 = \frac{1}{2} \times m \times 784\)
\(470000 = 392m\)
\(m = \frac{470000}{392} = 1198.98 \approx 1200\text{ kg}\)
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic P1.6.1 — Energy (Part (a))
• Topic P1.6.2 — Work (Part (b)(i))
• Topic P1.2 — Motion (Part (b)(ii), (b)(iii))
(a)(i) Chemical energy store
The battery stores chemical energy, which is converted to electrical energy when the circuit is complete.
(a)(ii) Chemical → Electrical
Energy is transferred from the battery to the lamp as electrical energy.
(a)(iii) Electrical → Light and Thermal
The lamp transfers electrical energy to the surroundings as light and thermal (heat) energy.
(b)(i) Change in gravitational potential energy:
ΔEₚ = mgΔh = 70 × 9.8 × 5.0 = 3430 J (≈ 3400 J)
(b)(ii) Kinetic energy just before entering the water = 3430 J
By conservation of energy, the gravitational potential energy lost is converted to kinetic energy (assuming no energy loss to friction).
(b)(iii) Speed:
Eₖ = ½mv²
3430 = 0.5 × 70 × v²
v² = 3430 ÷ 35 = 98
v = √98 = 9.9 m/s
