IGCSE Physics 0625 Paper 4 Practice Paper: Forces, Motion, Momentum, Pressure and Energy (Extended Theory, 100 marks)

Level: Year 10-11 (IGCSE) | Subject: Physics 0625 | Time: 60 minutes | Total: 100 marks | Parts: 33

Paper at a glance

Paper	Time	Marks	Calculator
Paper 4 (Extended, structured)	1 h 15 min	75	Not allowed

Questions

Question 1 (12 marks) – Kinematics: speed, acceleration and braking distance

(a) State the definitions of speed and acceleration and give the SI unit of each. (2 marks)

(b) A car accelerates uniformly from rest to 24 m/s in 8.0 s. Calculate its average acceleration. (3 marks)

(c) For the car in part (b), calculate the distance travelled in these 8.0 s. (3 marks)

(d) The car then travels at 24 m/s and brakes with a uniform deceleration of 6.0 m/s^2. Calculate the distance travelled before it stops. (4 marks)

Question 2 (18 marks) – Forces, Newton laws and momentum

(a) Write down the equation for Newton second law and state what each symbol represents. (2 marks)

(b) A car of mass 1200 kg accelerates at 3.0 m/s^2. Calculate the resultant force on the car. (3 marks)

(c) A ball of mass 0.15 kg hits a wall at 20 m/s and rebounds at 20 m/s in the opposite direction. Calculate the change in momentum of the ball. (4 marks)

(d) In part (c) the ball is in contact with the wall for 0.020 s. Calculate the average force exerted by the wall on the ball. (4 marks)

(e) A trolley of mass 2.0 kg moving at 3.0 m/s collides with a stationary trolley of mass 1.0 kg and they stick together. Calculate their common velocity after the collision. (3 marks)

(f) Explain how an air bag reduces injury to a passenger during a crash. (2 marks)

Question 3 (16 marks) – Pressure, hydraulics and upthrust

(a) Write down the equation for pressure and give its SI unit. (2 marks)

(b) A student of weight 600 N stands on both feet with a total contact area of 0.024 m^2. Calculate the pressure he exerts on the floor. (3 marks)

(c) Calculate the pressure due to water at a depth of 2.5 m. The density of water is 1000 kg/m^3 and g = 10 N/kg. (3 marks)

(d) A hydraulic press has a small piston of area 2.0 cm^2 and a large piston of area 40 cm^2. A force of 150 N is applied to the small piston. Calculate the force produced at the large piston. (4 marks)

(e) An object of volume 5.0 x 10^-4 m^3 is completely immersed in water. Calculate the upthrust on it and state whether it floats or sinks if it weighs 4.0 N. (4 marks)

Question 4 (18 marks) – Work, energy, power and efficiency

(a) Write down the equation for work done and give its SI unit. (2 marks)

(b) A box is pushed 12 m along the floor by a horizontal force of 250 N. Calculate the work done. (3 marks)

(c) A worker raises a 25 kg box 4.0 m at constant speed in 5.0 s. Calculate the gain in gravitational potential energy and the average power of the worker (g = 10 N/kg). (4 marks)

(d) A car of mass 800 kg travels at 15 m/s. Calculate its kinetic energy, and the average braking force if it stops after skidding 45 m. (4 marks)

(e) An electric motor has an input power of 500 W and a useful output power of 375 W. Calculate its efficiency. (3 marks)

(f) State two forms in which energy is commonly wasted during energy transfers. (2 marks)

Question 5 (18 marks) – Thermal physics: specific heat capacity, latent heat and heat transfer

(a) Define specific heat capacity. (2 marks)

(b) 2.0 kg of water is heated from 20 degrees C to 40 degrees C. Calculate the energy required (specific heat capacity of water = 4200 J/(kg degree C)). (4 marks)

(c) A heater has a power of 700 W. Calculate the time needed to heat the 2.0 kg of water from 20 degrees C to 40 degrees C, giving your answer in minutes. (4 marks)

(d) How much energy is needed to melt 0.50 kg of ice? The specific latent heat of fusion of ice is 3.34 x 10^5 J/kg. (4 marks)

(e) Give one example each of conduction, convection and radiation. (2 marks)

(f) Suggest two ways of reducing heat loss from a vacuum flask of hot water. (2 marks)

Question 6 (18 marks) – Electricity: resistance, series and parallel circuits and power

(a) Define resistance and give its SI unit. (2 marks)

(b) A 4.0 ohm resistor is connected to a 12 V supply. Calculate the current through it. (3 marks)

(c) For the resistor in part (b), calculate its power and the energy it transfers in 5.0 minutes. (4 marks)

(d) Two 6.0 ohm resistors are connected in series to a 12 V supply. Calculate the total resistance, the current and the voltage across each resistor. (4 marks)

(e) A 6.0 ohm and a 3.0 ohm resistor are connected in parallel to a 12 V supply. Calculate the equivalent resistance and the total current. (3 marks)

(f) Explain the purpose of a fuse in a circuit. (2 marks)

Answers and marking notes

Question 1 – Kinematics: speed, acceleration and braking distance

(a) Speed is the distance moved per unit time (m/s). Acceleration is the change of velocity per unit time (m/s^2). [2 marks]

(b) a = (v – u) / t = (24 – 0) / 8.0 = 3.0 m/s^2 (one mark equation, one mark substitution, one mark answer with unit). [3 marks]

(c) s = ut + 0.5at^2 = 0 + 0.5 x 3.0 x 8.0^2 = 96 m (one mark equation, one mark substitution, one mark answer). [3 marks]

(d) v^2 = u^2 + 2as, so 0 = 24^2 – 2 x 6.0 x s and s = 576 / 12 = 48 m (one mark equation, one mark substitution, one mark calculation, one mark unit). [4 marks]

Question 2 – Forces, Newton laws and momentum

(a) F = ma, where F is the resultant force in N, m the mass in kg and a the acceleration in m/s^2. [2 marks]

(b) F = ma = 1200 x 3.0 = 3600 N (one mark equation, one mark substitution, one mark answer with unit). [3 marks]

(c) p = mv = 0.15 x 20 = 3.0 kg m/s, so the change is 3.0 – (-3.0) = 6.0 kg m/s (one mark initial momentum, one mark direction, one mark subtraction, one mark unit). [4 marks]

(d) F = change in momentum / time = 6.0 / 0.020 = 300 N (one mark equation, one mark substitution, one mark calculation, one mark unit). [4 marks]

(e) Momentum is conserved: 2.0 x 3.0 = (2.0 + 1.0) x v, so v = 6.0 / 3.0 = 2.0 m/s (one mark conservation equation, one mark total mass, one mark answer). [3 marks]

(f) The air bag increases the time taken for the passenger to stop, so for the same change in momentum the average force is smaller and injury is reduced. [2 marks]

Question 3 – Pressure, hydraulics and upthrust

(a) p = F / A, measured in pascals (Pa), where 1 Pa = 1 N/m^2. [2 marks]

(b) p = 600 / 0.024 = 25 000 Pa (one mark equation, one mark substitution, one mark answer with unit). [3 marks]

(c) p = rho x g x h = 1000 x 10 x 2.5 = 25 000 Pa (one mark equation, one mark substitution, one mark answer). [3 marks]

(d) The pressure is the same: 150 / 2.0 = F / 40, so F = 150 x 40 / 2.0 = 3000 N (one mark equal pressure, one mark substitution, one mark calculation, one mark unit). [4 marks]

(e) Upthrust equals the weight of water displaced: 1000 x 10 x 5.0 x 10^-4 = 5.0 N. This is greater than the 4.0 N weight, so the net force is 1.0 N upwards and the object floats. [4 marks]

Question 4 – Work, energy, power and efficiency

(a) W = F x d, where the force is in the direction of the displacement, measured in joules (J). [2 marks]

(b) W = 250 x 12 = 3000 J (one mark equation, one mark substitution, one mark answer with unit). [3 marks]

(c) Gain in g.p.e. = mgh = 25 x 10 x 4.0 = 1000 J and P = 1000 / 5.0 = 200 W (one mark mgh, one mark value, one mark power equation, one mark answer). [4 marks]

(d) Ek = 0.5 x 800 x 15^2 = 90 000 J, and F = 90 000 / 45 = 2000 N (one mark kinetic energy equation, one mark value, one mark work equals energy, one mark answer). [4 marks]

(e) Efficiency = 375 / 500 x 100% = 75% (one mark equation, one mark substitution, one mark percentage). [3 marks]

(f) Thermal energy, produced by friction or resistance, and sound. [2 marks]

Question 5 – Thermal physics: specific heat capacity, latent heat and heat transfer

(a) The energy needed to raise the temperature of 1 kg of a substance by 1 degree C. [2 marks]

(b) E = mc x change in temperature = 2.0 x 4200 x 20 = 168 000 J (one mark equation, one mark temperature rise, one mark multiplication, one mark unit). [4 marks]

(c) t = E / P = 168 000 / 700 = 240 s = 4.0 minutes (one mark equation, one mark calculation, one mark conversion, one mark unit). [4 marks]

(d) E = mL = 0.50 x 3.34 x 10^5 = 167 000 J (one mark equation, one mark substitution, one mark calculation, one mark unit). [4 marks]

(e) Conduction: a metal spoon in hot soup becomes hot. Convection: an air conditioner circulates room air. Radiation: heat from the Sun reaches the Earth. [2 marks]

(f) Use a vacuum between the walls to stop conduction and convection, and silver the walls to reduce radiation, with a lid to reduce evaporation. [2 marks]

Question 6 – Electricity: resistance, series and parallel circuits and power

(a) The ratio of the voltage across a component to the current through it, measured in ohms (ohm). [2 marks]

(b) I = V / R = 12 / 4.0 = 3.0 A (one mark equation, one mark substitution, one mark answer with unit). [3 marks]

(c) P = VI = 12 x 3.0 = 36 W, and 5.0 minutes = 300 s so E = 36 x 300 = 10 800 J (two marks each). [4 marks]

(d) R = 6.0 + 6.0 = 12 ohm, I = 12 / 12 = 1.0 A and V = 1.0 x 6.0 = 6.0 V across each resistor (one mark each, plus one mark for the equal split). [4 marks]

(e) 1/R = 1/6.0 + 1/3.0, so R = 2.0 ohm and I = 12 / 2.0 = 6.0 A (one mark equivalent resistance, one mark equation, one mark answer). [3 marks]

(f) When the current is too large the fuse melts and breaks the circuit, preventing the cable from overheating and causing a fire. [2 marks]

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