Secondary 5 Combined Science Practice Paper: Forces And Motion, Energy And Power, Circuits And Electrical Energy, Waves And Light, Particles And Chemical Calculations, Acids, Bases And Redox

Secondary 5 Combined Science Practice Paper: Forces and Motion, Energy and Power, Circuits and Electrical Energy, Waves and Light, Particles and Chemical Calculations, Acids, Bases and Redox

2026-11-14

Combined Science – Secondary 5 – Practice Paper

S5 Combined Science paper with 24 parts on uniform acceleration, net force, impulse, free fall, kinetic and potential energy, power, efficiency。

Paper details　Secondary 5 Combined Science practice paper with 24 parts and worked answers on uniform acceleration, displacement, net force, engine thrust, impulse, average force, free fall, kinetic energy, gravitational potential energy, power, efficiency, energy loss, specific heat capacity, series resistance, parallel resistance, electricity consumption and cost, rated power, wave speed, refraction angle, echo distance, mole calculation, molar volume, concentration, dilution, particle number, titration volume, average rate and electrolysis mass.

Section A: Forces and Motion

Show the working and give answers to a sensible number of significant figures.

#	Question	Answer and marking notes
1	A car starts from rest and accelerates uniformly at 2.5 metres per second squared for 8.0 seconds. Find its final speed in metres per second and the displacement in metres.	Answer: v = u + at = 0 + 2.5 x 8.0 = 20.0 metres per second; s = ut + half a t squared = 0.5 x 2.5 x 8.0 squared = 80.0 metres.
2	A lorry of mass 1,200 kilograms moves horizontally with an acceleration of 1.8 metres per second squared against a resistive force of 450 newtons. Find the net force and the engine thrust.	Answer: net force = m a = 1,200 x 1.8 = 2,160 newtons; the thrust must also overcome friction, so thrust = 2,160 + 450 = 2,610 newtons.
3	A ball of mass 0.15 kilograms hits a wall at 18 metres per second and stops, the contact lasting 0.050 seconds. Find the impulse in newton seconds and the average force on the ball in newtons.	Answer: impulse = change in momentum = 0.15 x 18 = 2.70 newton seconds; average force = impulse divided by time = 2.70 / 0.050 = 54 newtons, directed opposite to the initial motion.
4	A stone falls freely from rest for 3.2 seconds, taking g as 9.8 metres per second squared. Find its final speed and the height fallen, then explain why the real height is usually slightly less than the calculated value.	Answer: v = g t = 9.8 x 3.2 = 31.36 metres per second; h = half g t squared = 0.5 x 9.8 x 3.2 squared = 50.18 metres. Air resistance acts upwards and reduces the acceleration, so the real height is smaller.

Section B: Energy and Power

Show the working and give energy in joules.

#	Question	Answer and marking notes
5	A bullet of mass 0.020 kilograms travels at 300 metres per second. Find its kinetic energy in joules.	Answer: kinetic energy = half m v squared = 0.5 x 0.020 x 300 squared = 900 joules.
6	An athlete of mass 65 kilograms runs up stairs of height 12 metres in 4.5 seconds, taking g as 9.8. Find the gain in gravitational potential energy in joules and the average power in watts.	Answer: potential energy = m g h = 65 x 9.8 x 12 = 7644 joules; average power = 7644 / 4.5 = 1699 watts.
7	A heater takes 1500 watts of electrical power and delivers 1,200 watts to the water. Find its efficiency as a percentage, the energy lost each second, and state two ways in which that energy is lost.	Answer: efficiency = 1,200 / 1500 x 100 = 80 per cent; 1,500 minus 1200 = 300 joules are lost each second, mainly by conduction and convection from the casing and by heating the heater body itself.
8	Water of mass 2.5 kilograms is heated from 20 degrees to 38 degrees, its specific heat capacity being 4200 joules per kilogram per degree. Find the energy needed in joules and the time in seconds for a 1,000 watt heater, ignoring losses.	Answer: E = m c delta T = 2.5 x 4200 x 18 = 189000 joules; time = 189000 / 2,000 = 94.5 seconds.

Section C: Circuits and Electrical Energy

Show the working and give currents to 2 decimal places.

#	Question	Answer and marking notes
9	Resistors of 6 ohms and 4 ohms are joined in series across a 12 volt supply. Find the current in amperes and the voltage across each resistor.	Answer: total resistance = 6 + 4 = 10 ohms; current = 12 / 10 = 1.20 amperes; the voltages are 1.20 x 6 = 7.2 volts and 1.20 x 4 = 4.8 volts.
10	Resistors of 6 ohms and 3 ohms are joined in parallel across a 12 volt supply. Find the equivalent resistance, the total current and the current in each branch.	Answer: one over R equals one over 6 plus one over 3, so R = 2.0 ohms; total current = 12 / 2.0 = 6.0 amperes; the branches take 2.0 and 4.0 amperes, which add up to the total.
11	A water heater rated at 2,000 watts runs for 3 hours a day for 30 days. Find the electricity used in kilowatt hours and the cost at 1.2 dollars per kilowatt hour.	Answer: 2,000 watts is 2.0 kilowatts; consumption = 2.0 x 3 x 30 = 180 kilowatt hours; cost = 180 x 1.2 = 216 dollars.
12	A lamp rated 60 watts is connected to a 220 volt supply. Find the current in amperes and the resistance in ohms, each to 3 significant figures.	Answer: current = 60 / 220 = 0.273 amperes; resistance = 220 / 0.273 = 807 ohms, or 807 ohms to 3 significant figures.

Section D: Waves and Light

Show the working and give angles to 2 decimal places.

#	Question	Answer and marking notes
13	A sound wave has a frequency of 250 hertz and a wavelength of 1.36 metres. Find its speed in metres per second and explain why the speed is fixed by the medium rather than by the frequency.	Answer: speed = frequency x wavelength = 250 x 1.36 = 340 metres per second. The speed depends on the elasticity and inertia of the medium, so a change of frequency changes the wavelength and leaves the product unchanged.
14	Light in air strikes glass of refractive index 1.5 at an angle of incidence of 30 degrees. Find the angle of refraction in degrees to 2 decimal places.	Answer: by Snell law, sin r equals sin 30 degrees divided by 1.5, giving 0.3333, so the angle of refraction is 19.47 degrees.
15	A sound made in front of a cliff returns as an echo after 1.2 seconds, the speed of sound being 340 metres per second. Find the distance to the cliff in metres.	Answer: the sound travels there and back, so the distance is 340 x 1.2 / 2 = 204 metres.
16	A monochromatic light has a vacuum wavelength of 600 nanometres and a wavelength of 400 nanometres in a medium, the speed of light in vacuum being 3.0 x 10 to the 8 metres per second. Find the refractive index of the medium and the frequency of the light inside it.	Answer: the refractive index is 600 / 400 = 1.5; frequency is set by the source and does not change with the medium, so it is 5.0 x 10 to the 14 hertz.

Section E: Particles and Chemical Calculations

Show the working and give amounts to 3 significant figures.

#	Question	Answer and marking notes
17	Calcium carbonate of mass 25.0 grams decomposes completely, its molar mass being 100 grams per mole and the Avogadro constant 6.02 x 10 to the 23. Find the amount in moles and the number of formula units present.	Answer: amount = 25.0 / 100 = 0.25 moles; the number of units is 0.25 x 6.02 x 10 to the 23, that is 1.51 x 10 to the 23.
18	A gas sample contains 0.50 moles and the molar volume at room conditions is 24,000 cubic centimetres. Find the volume in cubic centimetres and in cubic decimetres.	Answer: 0.50 x 24,000 = 12,000 cubic centimetres, which is 12 cubic decimetres.
19	A solute of 0.25 moles is dissolved to make 250 cubic centimetres of solution. Find the concentration in moles per cubic decimetre, then the concentration after water is added to 500 cubic centimetres.	Answer: 250 cubic centimetres is 0.25 cubic decimetres, so the concentration is 0.25 / 0.25 = 1.0 moles per cubic decimetre; after dilution it is 0.25 / 0.50 = 0.5, the amount of solute being unchanged.
20	A sample contains 1.2 x 10 to the 23 carbon dioxide molecules, the molar mass being 44 grams per mole and the Avogadro constant 6.02 x 10 to the 23. Find the amount in moles and the mass in grams to 3 significant figures.	Answer: amount = 1.2 x 10 to the 23 divided by 6.02 x 10 to the 23 = 0.199 moles; mass = 0.199 x 44 = 8.77 grams.

Section F: Acids, Bases and Redox

Show the working and write balanced formulae where needed.

#	Question	Answer and marking notes
21	Sodium hydroxide solution of volume 25.0 cubic centimetres and concentration 0.10 moles per cubic decimetre is neutralised by hydrochloric acid of concentration 0.15. Find the volume of acid needed in cubic centimetres to 2 decimal places.	Answer: the equation is one to one, so the amount is 0.10 x 25.0 / 1000 = 0.0025 moles and the volume is 0.0025 / 0.15 x 1000 = 16.67 cubic centimetres.
22	During a reaction the mass of solid falls from 5.00 grams to 3.20 grams in 40 seconds. Find the average rate in grams per second and per minute, and explain why the rate falls later in the reaction.	Answer: the rate is (5.00 – 3.20) / 40 = 0.045 grams per second, that is 2.7 grams per minute. Later the reactant concentration falls and collisions become less frequent, so the rate slows.
23	Find the oxidation number of manganese in potassium permanganate and of chromium in potassium dichromate, then explain why both act as oxidising agents in acidic solution.	Answer: in KMnO4 the potassium is plus 1 and each oxygen minus 2, so manganese is plus 7; in K2Cr2O7 the two potassiums give plus 2 and the seven oxygens minus 14, so the two chromium atoms total plus 12 and each is plus 6. Both are in their highest oxidation state, so they can only be reduced and therefore act as oxidising agents.
24	A current of 2.0 amperes passes through silver nitrate solution for 30 minutes, the Faraday constant being 96,500 coulombs per mole and the molar mass of silver 108 grams per mole. Find the mass of silver deposited at the cathode in grams to 3 significant figures.	Answer: the charge is 2.0 x 30 x 60 = 3600 coulombs; one electron deposits one silver atom, so the amount is 3600 / 96,500 = 0.0373 moles and the mass is 0.0373 x 108 = 4.03 grams.

Find a tutor — free Tutor Registration →

A TutorZone practice paper; original questions and passages, not publisher material.