AQA GCSE Combined Science: Trilogy Physics Paper 2 (Higher), 2019: Question 1

✅ Correct answer

7 s

Mark scheme note: an answer of 7(s) gains 2 marks.

💡 Key knowledge

• Velocity is increasing when the graph slopes upwards.
• Flat sections mean constant velocity, so they do not count.
• For this graph, velocity increases from 0 to 4 s and from 7 to 10 s.

🧠 Exam technique

• Add the two increasing intervals: 4 s + 3 s = 7 s.
• You can also do (4 - 0) + (10 - 7).
• Always read the time values from the axes carefully.

❌ Common errors

• Including the flat sections at 4–7 s or 10–14 s.
• Giving the time of the graph instead of the time spent increasing.
• Counting the decreasing section after 14 s.

✅ Correct answer

0.2 m/s² or -0.2 m/s²

Mark scheme note: an answer of 0.2 (m/s²) gains 2 marks.

📐 Calculations

1. Pick two points on the decelerating section, for example (14 s, 2 m/s) and (24 s, 0 m/s).
2. Find the change in velocity: 0 - 2 = -2 m/s.
3. Find the time change: 24 - 14 = 10 s.
4. Use gradient = change in velocity ÷ time:
   a = Δv / t = -2 / 10 = -0.2 m/s²

💡 Key knowledge

• On a velocity-time graph, the gradient gives acceleration.
• For a slowing object, the gradient is negative, so this is deceleration.
• Units must be m/s².

🧠 Exam technique

• You can use any two correct points on the straight sloping section.
• Show the substitution clearly to secure the method mark.
• If your answer is 0.2, that is acceptable even if you leave off the minus sign, because the question asks for deceleration.

❌ Common errors

• Using the wrong section of the graph.
• Forgetting to subtract correctly, especially with the velocity dropping to zero.
• Missing the units m/s².
• Writing speed instead of gradient.

✅ Correct answer

Because there are no wires to get tangled or disconnected.

Other accepted ideas: easier to move arms, wires are inconvenient, or easier to transfer data.

💡 Key knowledge

• Bluetooth is a wireless communication system.
• Wireless connections are useful in sport because movement is unrestricted.

🧠 Exam technique

This is a 1-mark suggestion question, so one clear reason is enough. Keep it simple and practical.

❌ Common errors

• Talking about charging, batteries, or screen brightness instead of the wireless link.
• Writing vague answers like “it is better”.

✅ Correct answer

wave speed = frequency × wavelength

v = fλ

💡 Key knowledge

• v = wave speed
• f = frequency
• λ = wavelength

🧠 Exam technique

Any correct rearrangement is accepted, but here the direct equation is best.

❌ Common errors

• Mixing up frequency and wavelength.
• Writing a formula with the wrong operation, such as division instead of multiplication.

✅ Correct answer

0.125 m or 0.13 m

Mark scheme note: an answer of 0.125 m or 0.13 m scores 3 marks.

📐 Calculations

1. Write the equation:
   v = fλ
2. Substitute the values:
   300 000 000 = 2 400 000 000 × λ
3. Rearrange:
   λ = 300 000 000 ÷ 2 400 000 000
4. Calculate:
   λ = 0.125 m

💡 Key knowledge

• Use the equation v = fλ .
• Speed of electromagnetic waves = 300 000 000 m/s.
• Frequency = 2 400 000 000 Hz.
• Final unit for wavelength is m.

🧠 Exam technique

• Always rearrange before substituting if that helps you avoid mistakes.
• Keep the values in standard units: Hz and m/s.
• Round sensibly: 0.125 m can be written as 0.13 m.

❌ Common errors

• Dividing in the wrong order.
• Forgetting the units.
• Leaving the answer as a very large number instead of a small wavelength.
• Using MHz or GHz without converting to Hz when required.

✅ Correct answers

Range is far enough for most uses.

Power is not too great so the battery will not drain quickly.

Also accepted: the phone will not overheat, or the range per milliwatt is greatest.

💡 Key knowledge

• Type 2 has 2.50 mW power and 10.0 m range.
• This is a practical balance between range and power use.
• In real devices, lower power usually helps conserve battery.

🧠 Exam technique

• You need two separate reasons for 2 marks.
• Use the table data to support your answer.
• Comparative statements are strong: for example, “range is enough” and “power is not too high”.

❌ Common errors

• Choosing the strongest power or longest range without explaining why it is suitable.
• Repeating the same idea in different words.
• Ignoring the data in the table.

💡 Top-level responses

• Used the graph accurately and only counted the increasing parts.
• Showed the calculation method for deceleration clearly.
• Used the exact physics equation v = fλ .
• Gave short, relevant reasons for the Bluetooth choice using the table.

❌ Where students lost marks

• Misreading the graph intervals.
• Giving acceleration without units, or with wrong sign/number.
• Not converting the wave equation correctly.
• Writing general statements instead of data-based reasons in part (f).

🧠 Must-remember points

• Upward slope on a velocity-time graph = increasing velocity.
• Gradient of a velocity-time graph = acceleration.
• Bluetooth is wireless, so no wires to tangle.
• v = fλ
• Always include units: s, m/s², m, Hz.

📐 Fast answers

• 01.1: 7 s
• 01.2: 0.2 m/s²
• 01.3: No wires to tangle/disconnect
• 01.4: v = fλ
• 01.5: 0.125 m
• 01.6: Enough range + low enough power to save battery