Total marks: 60 · Duration: 1 hour 30 minutes
Instructions to candidates
• Answer all questions. • Use black ink or black ball-point pen. • The number of marks is given in brackets [ ] at the end of each question or part question. • Show all your working in calculations; credit may be given for a correct method. • The following equations may be useful: KE = ½mv²; GPE = mgh (g = 10 N/kg); V = IR; P = VI; wave speed = f × λ; energy = mass × specific heat capacity × temperature change. • The total number of marks for this paper is 60. • All data you need is given within the questions.
Paper
Section A — Structured Questions (44 marks)
1. Forces and motion
(a) A car of mass 900 kg accelerates at 2.5 m/s². Calculate the resultant force acting on the car. [3]
(b) State two factors that would increase the braking distance of a car. [2]
(c) A skydiver reaches a constant (terminal) velocity while falling. Explain, in terms of the forces acting on the skydiver, why the velocity becomes constant. [4]
2. Energy
(a) A ball of mass 0.5 kg is lifted to a height of 8 m. Calculate the gravitational potential energy gained. (g = 10 N/kg) [3]
(b) The ball is then dropped. Calculate its kinetic energy just before it hits the ground, assuming no air resistance, and hence calculate its speed at that point. [4]
(c) In a real drop, the speed is slightly lower than your calculated value. Explain why, in terms of energy transfer. [2]
3. Electricity
(a) A resistor has a potential difference of 12 V across it and a current of 0.5 A flowing through it. Calculate its resistance. [3]
(b) State what happens to the total resistance when two resistors are connected in parallel rather than in series. [2]
(c) Calculate the power of the resistor in part (a), and the energy it transfers in 2 minutes. [4]
4. Waves
(a) A wave has a frequency of 400 Hz and travels at 340 m/s. Calculate its wavelength. [3]
(b) The electromagnetic spectrum includes radio waves, visible light and gamma rays. Put these three in order of increasing frequency, and give one use of radio waves. [3]
(c) Explain what is meant by the refraction of a wave and state what causes it. [3]
5. Thermal physics
(a) Calculate the energy needed to raise the temperature of 2 kg of water by 15 °C. (Specific heat capacity of water = 4200 J/kg°C) [4]
(b) Explain, in terms of the arrangement and movement of particles, the difference between a solid and a gas. [4]
Section B — Extended Response (16 marks)
6. A fixed mass of gas is kept at constant temperature in a sealed container with a movable piston.
(a) Explain, in terms of the motion of its particles, how a gas exerts pressure on the walls of its container. [4]
(b) The gas has a volume of 0.020 m³ at a pressure of 100 kPa. The piston is pushed in so that the volume decreases to 0.008 m³, at constant temperature. Calculate the new pressure of the gas, and explain in terms of particles why the pressure changes. [6]
7. Describe how electricity can be generated using a renewable energy resource of your choice, and discuss one advantage and one disadvantage of using this resource compared with fossil fuels. [6]