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 = rac{Δv}{t} where Δv = v_f - v_i.

Using the equation from part (b)(i), we can calculate the acceleration:

1. Determine the change in velocity:

   Δv = v_f - v_i = 20 ext{ m/s} - 2 ext{ m/s} = 18 ext{ m/s}

2. Calculate the acceleration:

   a = rac{Δv}{t} = rac{18 ext{ m/s}}{12 ext{ s}} = 1.5 ext{ m/s}^2.

To find the distance traveled by the cyclist using the velocity-time graph in Figure 10, we calculate the area under the graph:

1. The graph is a triangle with a base of 15 s and a height of 7 m/s.

2. The formula for the area of a triangle is:

   Area = rac{1}{2} imes ext{base} imes ext{height}

3. Substituting the values:

   Area = rac{1}{2} imes 15 ext{ s} imes 7 ext{ m/s} = 52.5 ext{ m}.

Thus, the cyclist travels a distance of 52.5 m.

The stopping distance of a car can be affected by various factors involving the driver:

1. Reaction Time: A driver’s reaction time can significantly impact how quickly they can respond to a potential hazard. Increased reaction time leads to longer stopping distances.

2. Tiredness: A tired driver is less alert and may take longer to react, resulting in increased stopping distances.

3. Distractions: If a driver is distracted (e.g., using a phone), their ability to respond quickly is impaired, thus increasing stopping distances.

Examples: A driver who is engaged in a conversation or checking their phone may not respond swiftly to sudden changes on the road, leading to longer stopping distances.

The stopping distance of a car is influenced by several factors related to the car and the road:

1. Speed of the Car: The faster a car is traveling, the longer the stopping distance because it takes more time to come to a complete stop.

2. Condition of the Brakes: Effective brakes decrease stopping distances, while worn brakes increase them.

3. Type of Tyres: Tyre quality and tread depth can greatly impact grip on the road. Worn or unsuitable tyres can lead to longer stopping distances.

4. Surface of the Road: A wet or slippery road surface increases stopping distances due to reduced traction.

Examples: If a car has worn-out tyres and is traveling on a wet road, it will take much longer to stop compared to a car with good tyres on a dry road.