Calculation of Gravitational Potential Energy

1. Formula: The change in gravitational potential energy (GPE) can be calculated using the formula: $\text{GPE} = mgh$ Where:

   • $m$ = mass (75 kg)
   • $g$ = gravitational field strength (10 N/kg)
   • $h$ = height difference (20 m)

2. Substituting the values: $\text{GPE} = 75\,\text{kg} \times 10\,\text{N/kg} \times 20\,\text{m}$ $\text{GPE} = 15000\,\text{J}$

Thus, the change in gravitational potential energy of the cyclist is 15,000 J.

Using the Provided Formula

1. Formula: The distance travelled during acceleration is given by: $x = \frac{v^{2} - u^{2}}{2a}$ Where:

   • $v$ = final velocity (80 m/s)
   • $u$ = initial velocity (0 m/s)
   • $a$ = acceleration (4 m/s²)

2. Substituting the values: $x = \frac{(80)^2 - (0)^2}{2 \times 4}$ $x = \frac{6400}{8}$ $x = 800\,\text{m}$

The distance travelled by the aircraft while it is accelerating is 800 m.

The extra piece of apparatus needed to determine the average speed is a stopwatch.

The student can make the trolley accelerate by attaching a weight to one end of the string that is connected to the trolley. By allowing the weight to drop, the force of gravity will pull on the string, causing the trolley to move along the bench.

The student must also measure the time taken for the trolley to travel between the two marks. This measurement can be used alongside the distance to calculate acceleration.