Questions and Answers
What is the effect of doubling the speed of a car on the braking distance, assuming the braking force remains constant?
When calculating distance travelled during acceleration, which equation is likely used?
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?
What factors can influence the braking distance of a car, apart from speed?
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What is the relationship between kinetic energy and braking distance?
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Which of the following calculations is essential for determining the distance travelled while accelerating?
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During an emergency stop, which scenario would likely result in a shorter braking distance?
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If a car's speed is increased from 30 m/s to 60 m/s, how does the kinetic energy change?
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Which statement best describes the motion of the car when horizontal forces are balanced?
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What is the correct equation to calculate distance travelled using speed and time?
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How do you calculate the acceleration of the car if it speeds up from 9m/s to 18m/s in 6 seconds?
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Which equation correctly relates resultant force, mass, and acceleration?
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If the mass of the car is 1120 kg and the driver's mass is 80 kg, what would their total mass be?
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What is the resultant force acting on the car if its total mass is 1200 kg and it accelerates at 3 m/s²?
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What would happen if the resultant force acting on the car becomes zero?
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Which of the following describes a scenario in which the car is speeding up?
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What is the useful energy output from an electric motor used to lift a load?
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What typically happens to the wasted energy in an electric motor?
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Based on the graph, what can be concluded about the relationship between the load lifted and input energy needed?
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Why are some escalators turned off when the shop is not busy?
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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?
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How much does it cost to run one escalator for an average week?
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What is the average power of one escalator motor mentioned in the content?
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What energy type is primarily not useful in the operation of an electric motor lifting a load?
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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.
