Forces and Motion: Motion and Graphs

IGCSE Edexcel Physics
1.1–1.10 Units, Speed, Acceleration and Graphs
Key Concept: Motion can be described using distance-time and velocity-time graphs. Use $v = d/t$, $a = (v - u)/t$ and $v^2 = u^2 + 2as$.

Section A: Units

1. State the SI unit for: mass, distance, time, speed, acceleration, force and gravitational field strength. [7]

Section B: Distance-Time Graphs

2. Describe what the gradient of a distance-time graph represents. [2]
3. A cyclist travels 300 m in 20 s. Calculate the average speed. [2]

Section C: Velocity-Time Graphs

4. Explain what the gradient and area of a velocity-time graph represent. [4]
5. A car increases speed from 5 m/s to 25 m/s in 4 s. Calculate the acceleration. [2]
6. A car travels at 20 m/s for 6 s. Calculate the distance travelled from the v–t graph. [2]

Section D: SUVAT Equation

7. A runner accelerates from rest at $2\,m/s^2$ for 15 m. Find the final speed using $v^2 = u^2 + 2as$. [3]

Total: [21 marks]

Mark Scheme

1. kg, m, s, m/s, $m/s^2$, N, N/kg [7]
2. Gradient is speed [2]
3. $v = d/t = 300/20 = 15\,m/s$ [2]
4. Gradient = acceleration; area = distance travelled [4]
5. $a = (v - u)/t = (25 - 5)/4 = 5\,m/s^2$ [2]
6. Distance = area = $20 \times 6 = 120\,m$ [2]
7. $v^2 = 2 \times 2 \times 15 = 60$; $v \approx 7.7\,m/s$ [3]