Physics Forces on a Car Quiz

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Questions and Answers

What is the effect of doubling the speed of a car on the braking distance, assuming the braking force remains constant?

The braking distance remains the same.

The braking distance doubles.

The braking distance quadruples. (correct)

The braking distance halves.

When calculating distance travelled during acceleration, which equation is likely used?

Distance = Initial Velocity × Time + 0.5 × Acceleration × Time² (correct)

Speed = Distance / Time

Distance = Time × Acceleration

Velocity = Distance / Time + Acceleration

If a car has an initial speed of 20 m/s and the braking force remains unchanged, what will happen to the kinetic energy when the speed is increased to 40 m/s?

Kinetic energy decreases.

Kinetic energy increases fourfold. (correct)

Kinetic energy doubles.

Kinetic energy remains constant.

What factors can influence the braking distance of a car, apart from speed?

All of the above Signup and view all the answers

What is the relationship between kinetic energy and braking distance?

Increased kinetic energy increases braking distance. Signup and view all the answers

Which of the following calculations is essential for determining the distance travelled while accelerating?

Initial Velocity + Time × Acceleration Signup and view all the answers

During an emergency stop, which scenario would likely result in a shorter braking distance?

Greater braking force Signup and view all the answers

If a car's speed is increased from 30 m/s to 60 m/s, how does the kinetic energy change?

Changes from 900 J to 3600 J Signup and view all the answers

Which statement best describes the motion of the car when horizontal forces are balanced?

It will have a constant speed. Signup and view all the answers

What is the correct equation to calculate distance travelled using speed and time?

distance travelled = speed × time Signup and view all the answers

How do you calculate the acceleration of the car if it speeds up from 9m/s to 18m/s in 6 seconds?

acceleration = (final speed - initial speed) / time Signup and view all the answers

Which equation correctly relates resultant force, mass, and acceleration?

resultant force = mass × acceleration Signup and view all the answers

If the mass of the car is 1120 kg and the driver's mass is 80 kg, what would their total mass be?

1300 kg Signup and view all the answers

What is the resultant force acting on the car if its total mass is 1200 kg and it accelerates at 3 m/s²?

3000 N Signup and view all the answers

What would happen if the resultant force acting on the car becomes zero?

The car will continue moving at its current speed. Signup and view all the answers

Which of the following describes a scenario in which the car is speeding up?

There is a net force propelling the car forward. Signup and view all the answers

What is the useful energy output from an electric motor used to lift a load?

Mechanical energy Signup and view all the answers

What typically happens to the wasted energy in an electric motor?

It dissipates as heat Signup and view all the answers

Based on the graph, what can be concluded about the relationship between the load lifted and input energy needed?

More load requires more input energy. Signup and view all the answers

Why are some escalators turned off when the shop is not busy?

To save energy and reduce costs Signup and view all the answers

If an escalator motor has a power of 4000 W and runs for 8 hours daily, how many kilowatt-hours does it consume in a week?

32 kWh Signup and view all the answers

How much does it cost to run one escalator for an average week?

£4.80 Signup and view all the answers

What is the average power of one escalator motor mentioned in the content?

4000 W Signup and view all the answers

What energy type is primarily not useful in the operation of an electric motor lifting a load?

Sound energy Signup and view all the answers

Study Notes

Motion of the Car

Car can be stationary, have constant speed, speed up, or slow down based on forces acting on it.
Constant speed implies no net acceleration resulting from balanced forces.

Distance, Speed, and Time

Distance can be calculated using the equation: distance travelled = speed × time.

Acceleration Calculation

Acceleration determined by formula:
- acceleration = (final speed - initial speed) / time
For a car accelerating from 9 m/s to 18 m/s in 6 seconds:
- acceleration = (18 m/s - 9 m/s) / 6 s = 1.5 m/s²

Resultant Force and Acceleration

The relationship between acceleration, mass, and resultant force is given by:
- resultant force = mass × acceleration.

Calculating Resultant Force

Total mass of car and driver = 1120 kg + 80 kg = 1200 kg.
Resultant force during acceleration calculated with the previously defined equation.

Distance During Acceleration

Use kinematic equations to calculate distance while accelerating, formula typically involves initial speed, time, and acceleration.

Braking Distance and Kinetic Energy

Braking distance increases quadratically with speed increase due to kinetic energy (KE = 1/2 mv²).
Doubling speed quadruples kinetic energy, leading to longer stopping distance.

Electric Motor Energy Transfer

Electric motor converts electrical energy into both useful and wasted energy.
Useful energy output is often mechanical energy used to lift loads.

Wasted Energy

Wasted energy often dissipates as heat, contributing to inefficiency in energy transfer.

Input Energy and Load Relationship

Increased load lifted by a motor results in higher input energy requirements, showcasing a direct relationship.

Escalator Energy Efficiency

Each escalator motor's power: 4000 W, operational for 8 hours/day, 6 days/week.
Electricity cost calculated by converting power to kilowatts and multiplying by time and cost per kilowatt-hour.
Costs to run one escalator can be determined via: cost = power (kW) × time (h) × price per kWh.

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Description

This quiz assesses your understanding of the principles of motion and how forces affect the movement of a car. It includes questions on the relationship between distance, speed, and time. Ensure you are familiar with Newton's Laws of Motion to excel.