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 is given by:

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

where:

• $a$ = acceleration
• $\Delta v$ = change in velocity
• $t$ = time taken.

To calculate acceleration, we can use the formula:

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

where the change in velocity, $\Delta v$, is: $\Delta v = 20 \text{ m/s} - 2 \text{ m/s} = 18 \text{ m/s}$

The time taken is given as 12 s. Thus:

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

So, the acceleration of the van is 1.5 m/s².

To calculate the distance traveled, we can use the area under the velocity-time graph. The graph shows a triangular area, which can be computed as follows:

Area = $\frac{1}{2} \times base \times height$

Here, the base is 15 s and the height is the maximum velocity of 7 m/s:

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

Thus, the cyclist travels 52.5 m.

The stopping distance of a car can be significantly impacted by several driver-related factors. For example:

• The driver's reaction time: A driver who is tired, distracted, or under the influence of drugs will have an increased reaction time, leading to a longer stopping distance.
• The type of footwear: Wearing inappropriate shoes (like high heels or flip-flops) can affect the driver's ability to quickly apply the brakes, increasing stopping distance.

Several factors regarding the car and road conditions can impact stopping distance:

• Mass/weight of the car: A heavier car requires a longer stopping distance compared to a lighter one due to its greater momentum.
• Condition of brakes and tyres: Worn or poorly maintained brakes will reduce the car's ability to stop quickly, thereby increasing stopping distance. Similarly, worn tyres can lead to reduced grip on the road surface, contributing to longer stopping distances.
• Road conditions: Wet or icy roads can significantly increase stopping distance as they reduce the friction between the tyres and the road.