The remote control transmits radio waves to the car aerial - AQA - GCSE Physics - Question 6 - 2020 - Paper 1

When the car aerial absorbs the radio waves:

1. An alternating current is induced in the electrical circuit, resulting from the oscillation of the electric and magnetic fields present in the radio wave.
2. The electrons in the circuit vibrate or oscillate with the same frequency as the incoming radio waves.

1. Radio waves are electromagnetic waves, while sound waves are mechanical waves.
2. Radio waves can travel through a vacuum, whereas sound waves require a medium (such as air or water) to propagate.

The car is accelerating during the first 30 seconds of motion.

To find the speed ( ( v ) ) of the car after 20 seconds, we can use the relationship:

1. The initial speed is assumed 0, and using the previously given values, we find:
   • Speed after 20 seconds, if a certain acceleration is assumed (e.g., 0.28 m/s as calculated from a graph), will be used here: $v = 0.28 \times 20 = 5.6 \, \text{m/s}$ Hence, the speed of the car is ( 5.6 , \text{m/s} ).

The resultant force ( ( F ) ) can be calculated using Newton's second law:

where:

• The mass of the car (assumed from work-energy principle or other context as needed)
• The acceleration = ( 0.040 , \text{m/s}^2 )

Using work done = 0.48 J, and displacement as calculated:

• Rearranging, we can find:

The car reaches a maximum speed when:

1. The driving force provided by the motor equals the resistive forces acting against it (like friction and air resistance).
2. As speed increases, air resistance increases, making it harder for the car to accelerate further.
3. Eventually, resistive forces balance the driving force, causing the car to travel at a constant speed, known as terminal velocity.