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P5: Quiz 17 – Answers
P5: Quiz 17 – Answers
1) When a car brakes, energy is transferred from the car’s kinetic energy stores to the thermal energy stores of the brakes and the surroundings. This energy is transferred because of friction between the brake pads and the wheels/ brakes. As energy is transferred, work has been done
2)
a) Deceleration is 18 m/s2 (accept -18 m/s2)
b) 25,200 N
3) 39,000 N
Questions
1) Describe the energy transfers when a car is braking.
2) A car that is travelling at 30 m/s performs an emergency stop. The braking distance for the emergency stop is 25 metres. The car has a mass of 1,400 kg.
a) Calculate the deceleration.
b) Calculate the braking force.
3) A van that is travelling at 24 m/s performs an emergency stop. The braking distance for the emergency stop is 26 metres. The van has a mass of 3,500 kg.
Calculate the braking force. Give your answer to 2 significant figures.
1) Describe the energy transfers when a car is braking.
2) A car that is travelling at 30 m/s performs an emergency stop. The braking distance for the emergency stop is 25 metres. The car has a mass of 1,400 kg.
a) Calculate the deceleration.
b) Calculate the braking force.
3) A van that is travelling at 24 m/s performs an emergency stop. The braking distance for the emergency stop is 26 metres. The van has a mass of 3,500 kg.
Calculate the braking force. Give your answer to 2 significant figures.