This set practises four skills from physical reasoning in mixed tasks: rates from graphs, energy in circuits, thermal explanations and pressure. Questions run from easy to harder, and all data is invented.
Work on paper, show every step, write units, and only then open the answer. Use g = 10 N/kg. The scientific investigation critic and tool T04 are useful for checking method and working.
Questions
1. (graph rate) A straight line on a distance-time graph passes through (0 s, 0 m) and (5 s, 20 m). Find the speed.
Show answer
Change in distance = 20 m, change in time = 5 s. Speed = 20 ÷ 5 = 4 m/s.
2. (graph rate) A straight line passes through (3 s, 6 m) and (9 s, 24 m). Find the speed.
Show answer
Change in distance = 24 − 6 = 18 m. Change in time = 9 − 3 = 6 s. Speed = 18 ÷ 6 = 3 m/s. Dividing 24 by 9 would give 2.7 m/s, which is wrong because the line does not start at the origin.
3. (graph rate) A cooling graph is a straight line from 90 °C at 0 min to 60 °C at 10 min. Find the cooling rate.
Show answer
Change in temperature = 90 − 60 = 30 °C over 10 min. Rate = 30 ÷ 10 = 3 °C/min.
4. (graph rate) On a speed-time graph a straight line rises from 0 m/s to 12 m/s in 4 s. Find the acceleration.
Show answer
Acceleration = gradient = 12 ÷ 4 = 3 m/s².
5. (circuit energy) A lamp has a current of 0.40 A when the potential difference across it is 9.0 V. Find its power.
Show answer
P = I × V = 0.40 × 9.0 = 3.6 W.
6. (circuit energy) How much energy does the lamp in question 5 transfer in 50 s?
Show answer
E = P × t = 3.6 × 50 = 180 J.
7. (circuit energy) The same lamp stays on for 2.0 minutes. Find the energy transferred, and explain why 3.6 × 2.0 is the wrong calculation.
Show answer
Convert the time: 2.0 min = 120 s. E = 3.6 × 120 = 432 J. The watt means joules per second, so using 2.0 minutes would give 7.2, which is not a quantity in joules.
8. (pressure) A force of 300 N acts on an area of 0.0050 m². Find the pressure.
Show answer
p = F ÷ A = 300 ÷ 0.0050 = 60 000 Pa.
9. (biological pressure) A child of mass 36 kg stands with a total foot area of 240 cm² touching the ground. Find the pressure on the ground in Pa.
Show answer
W = 36 × 10 = 360 N. Area = 240 ÷ 10 000 = 0.0240 m². p = 360 ÷ 0.0240 = 15 000 Pa.
10. (thermal models) Water in a pan boils at a steady temperature while the hob keeps heating. Explain this using both the energy-transfer model and the particle model.
Show answer
Thermal energy keeps transferring from the hob to the water. The energy is used to overcome the attractions between particles so they separate into steam, which changes their arrangement. The average kinetic energy of the particles does not increase, so the temperature stays constant until the water has boiled away.
11. (tier and units) Change 36 km/h into m/s, then say which step of the routine in the tier lesson you would do before spending time on a speed calculation like this.
Show answer
36 km/h = 36 000 m per 3600 s = 36 000 ÷ 3600 = 10 m/s. Before practising, check in your syllabus whether the relationship is marked for your route, and check how equations appear in specimen papers.
If you got these wrong
- Questions 1 to 4: you probably divided one reading, or lost the unit. Review moving from a graph to a rate calculation.
- Questions 5 to 7: check for a missing time conversion or a swapped quantity. Review connecting a circuit observation with energy transfer.
- Question 10: a missing half of the answer is the usual cause. Review explaining a thermal change using two models.
- Questions 8 and 9: look for mass used as force or area left in cm². Review applying a force relationship to a biological measurement.
- Question 11: review checking whether a numerical relationship belongs in the learner’s tier.
If a pattern of errors stays after revisiting the lessons, our teachers can work through it with you in online one-to-one Combined Science tuition.