6 (a) Which of these is a vector? A energy B force C mass D work (b) (i) State the equation that relates acceleration to change in velocity and time taken - Edexcel - GCSE Physics Combined Science - Question 6 - 2020 - Paper 1

The equation that relates acceleration (a) to change in velocity (Δv) and time (t) is given by:

$a = \frac{\Delta v}{t}$

where Δv is the change in velocity, calculated as final velocity minus initial velocity.

To calculate the acceleration of the van, we can use the formula:

$a = \frac{\Delta v}{t}$

where:

• Initial velocity (u) = 2 m/s
• Final velocity (v) = 20 m/s
• Time (t) = 12 s

First, we calculate the change in velocity:

$\Delta v = v - u = 20 \, \text{m/s} - 2 \, \text{m/s} = 18 \, \text{m/s}$

Now, substituting the values into the acceleration formula:

$a = \frac{18 \, \text{m/s}}{12 \, \text{s}} = 1.5 \, \text{m/s}^2$

To find the distance traveled by the cyclist using the velocity-time graph:

The area under the graph represents the distance.

The graph appears to be a triangle with:

• Base (time) = 15 s
• Height (velocity) = 7 m/s

The area of a triangle is given by:

$\text{Area} = \frac{1}{2} \times \text{Base} \times \text{Height}$

Substituting the values:

$\text{Distance} = \frac{1}{2} \times 15 \, \text{s} \times 7 \, \text{m/s} = 52.5 \, \text{m}$

The stopping distance of a car can be significantly affected by various driver-related factors:

1. Tiredness: A tired driver may have delayed reaction times leading to increased stopping distances.

2. Distractions: If a driver is distracted (e.g., using a mobile phone), this may result in slower response times.

3. Experience: An experienced driver may react more swiftly than a novice, thereby reducing stopping distance.

4. Type of footwear: Wearing inappropriate shoes can hinder the driver's ability to apply the brakes effectively.

Several factors related to the car or the road that affect stopping distance include:

1. Mass/Weight of Car: Heavier cars will require a longer distance to stop compared to lighter ones due to inertia.

2. Condition of Tyres: Worn-out or under-inflated tyres decrease traction, leading to longer stopping distances.

3. Road Surface: Wet or icy roads can significantly increase the distance needed to stop due to decreased friction.

4. State of Brakes: Well-maintained brakes will respond better, reducing stopping distance while faulty brakes may lead to much longer distances.