Work, Energy, and Power are fundamental concepts in Physics that explain how force produces motion, how energy is transferred, and how quickly work is done. These concepts are frequently tested in the TNPSC General Science section. Attempt this TNPSC Physics Work Energy Power Quiz 1 to strengthen your understanding and improve your exam preparation.
TNPSC Physics Work, Energy and Power Quiz 1 – Detailed Explanations
Work is said to be done when a force causes an object to move. The ability to do work is called energy, while power is the rate at which work is completed. Understanding different forms of energy, the law of conservation of energy, work done, and power helps explain many everyday phenomena and forms an important part of the TNPSC Physics syllabus.
1. Work is said to be done when:
In Physics, work is said to be done only when a force applied on an object causes it to move (displacement) in the direction of the force. Simply applying a force without any movement does not result in work being done. For example, pushing a wall without moving it does not involve work in the scientific sense, whereas lifting a book from the floor to a table involves work because the object moves against gravity. Work depends on both the magnitude of the force and the displacement produced, making it an important concept in understanding motion and energy.
Key Points
- Work requires both force and displacement.
- No displacement means no work is done.
- Work depends on the direction of force.
- Work is a scalar quantity.
- SI unit of work is the joule (J).
✅ Correct Answer: B. Force causes displacement
2. The SI unit of work is:
The joule (J) is the SI unit of work and energy. One joule of work is done when a force of one newton moves an object through a distance of one metre in the direction of the applied force. Since work and energy are closely related, both are measured using the same unit. The joule is named after the English physicist James Prescott Joule, whose experiments greatly contributed to the understanding of energy and heat. This unit is widely used in Physics to measure work, energy, and heat.
Key Points
- The SI unit of work is joule (J).
- 1 Joule = 1 Newton × 1 metre.
- Work and energy share the same SI unit.
- Named after James Prescott Joule.
- Joule is also used to measure energy and heat.
✅ Correct Answer: A. Joule
3. Work done is calculated as:
The amount of work done depends on both the force applied and the displacement of the object in the direction of that force. Mathematically, work is calculated using the formula Work = Force × Displacement. If the object does not move, the displacement is zero, and therefore no work is done, regardless of how much force is applied. This formula helps explain how energy is transferred when objects are moved and is one of the basic equations used in Physics to solve numerical problems.
Key Points
- Work = Force × Displacement (W = F × s).
- Displacement must occur for work to be done.
- Greater force or displacement results in more work.
- SI unit of work is the joule (J).
- The formula is widely used in Physics calculations.
✅ Correct Answer: B. Force × Distance
4. Energy is defined as the ability to:
Energy is the capacity or ability of an object or system to do work. Every activity around us, such as walking, lifting objects, running machines, or producing electricity, requires energy. Energy exists in many forms, including kinetic, potential, heat, light, sound, chemical, and electrical energy. It can be converted from one form to another, but according to the Law of Conservation of Energy, it can neither be created nor destroyed. Understanding energy helps explain how physical processes occur in everyday life.
Key Points
- Energy is the capacity to do work.
- It exists in many different forms.
- Energy can be transformed from one form to another.
- Energy cannot be created or destroyed.
- SI unit of energy is the joule (J).
✅ Correct Answer: B. Do work
5. The SI unit of energy is:
The joule (J) is the SI unit used to measure energy. It represents the amount of energy transferred when one newton of force moves an object by one metre in the direction of the force. Since work and energy are closely related, both use the same SI unit. Energy is essential for all natural and human-made processes, from moving vehicles to operating electrical appliances. Measuring energy in joules helps scientists and engineers calculate energy transfer accurately in various physical systems.
Key Points
- Energy is measured in joules (J).
- Work and energy have the same SI unit.
- Energy is required to perform work.
- Energy exists in various forms.
- Joule is the standard SI unit used worldwide.
✅ Correct Answer: A. Joule
6. Which of the following is kinetic energy?
Kinetic energy is the energy possessed by an object due to its motion. Every moving object, whether it is a rolling ball, a moving vehicle, flowing water, or a flying bird, has kinetic energy. The amount of kinetic energy depends on the mass of the object and the square of its velocity. This means that increasing the speed of an object greatly increases its kinetic energy. The SI unit of kinetic energy is the joule (J). Understanding kinetic energy helps explain the motion of objects and energy transformations in everyday life.
Key Points
- Kinetic energy is the energy of motion.
- It depends on the mass and velocity of an object.
- Greater speed results in greater kinetic energy.
- SI unit of kinetic energy is the joule (J).
- Examples include moving vehicles, flowing water, and flying birds.
✅ Correct Answer: B. Energy due to motion
7. Potential energy is energy due to:
Potential energy is the energy possessed by an object because of its position or configuration. An object placed at a height stores gravitational potential energy due to the force of gravity. Similarly, a stretched rubber band or compressed spring stores elastic potential energy. This stored energy can be converted into kinetic energy when the object begins to move. The amount of gravitational potential energy depends on the mass of the object, height, and acceleration due to gravity. Potential energy plays an important role in many natural and mechanical systems.
Key Points
- Potential energy is stored energy.
- It depends on the position or configuration of an object.
- Water stored in a dam has gravitational potential energy.
- A stretched spring stores elastic potential energy.
- SI unit of potential energy is the joule (J).
✅ Correct Answer: B. Position
8. The formula for kinetic energy is:
The kinetic energy of a moving object is calculated using the formula KE = ½ mv², where m is the mass of the object and v is its velocity. This formula shows that kinetic energy increases directly with mass and increases rapidly with the square of the velocity. For example, doubling the speed of an object increases its kinetic energy by four times. This concept is widely used in Physics, engineering, transportation, and sports to study the motion and impact of moving objects.
Key Points
- Formula: KE = ½ mv².
- Kinetic energy depends on mass and velocity.
- Increasing velocity greatly increases kinetic energy.
- SI unit of kinetic energy is the joule (J).
- Applicable only to moving objects.
✅ Correct Answer: A. ½ mv²
9. The energy stored in a stretched rubber band is:
When a rubber band is stretched, work is done on it, and this work is stored as elastic potential energy. This stored energy remains within the object as long as it is stretched or compressed. Once released, the elastic potential energy is converted into kinetic energy, causing the rubber band to return to its original shape. Springs, bows, and elastic bands are common examples of objects that store elastic potential energy. This type of energy is widely used in toys, sports equipment, and mechanical devices.
Key Points
- A stretched rubber band stores elastic potential energy.
- Energy is stored due to deformation.
- The stored energy converts into kinetic energy when released.
- Springs and bows also store elastic potential energy.
- Elastic potential energy is a form of potential energy.
✅ Correct Answer: B. Elastic Potential Energy
10. The SI unit of power is:
Power is the rate at which work is done or energy is transferred. The SI unit of power is the watt (W), named after the Scottish engineer James Watt. One watt is equal to one joule of work done per second. Power helps compare how quickly different machines and appliances perform the same amount of work. For example, a higher-wattage motor or bulb generally performs its function faster or consumes more energy per unit time than a lower-wattage one.
Key Points
- The SI unit of power is the watt (W).
- 1 Watt = 1 Joule per second.
- Power measures the rate of doing work.
- The unit is named after James Watt.
- Electrical appliances are rated in watts.
✅ Correct Answer: B. Watt
11. Power is defined as:
Power is the rate at which work is done or energy is transferred. It indicates how quickly a task is completed. Two people may do the same amount of work, but the one who completes it in less time is said to produce more power. Mathematically, power is calculated by dividing the work done by the time taken. This concept is widely used to compare the performance of machines, engines, motors, and electrical appliances. The SI unit of power is the watt (W), which represents one joule of work done in one second.
Key Points
- Power is the rate of doing work.
- Formula: Power = Work ÷ Time (P = W/t).
- SI unit of power is the watt (W).
- Greater power means more work is done in less time.
- Power is used to compare the efficiency of machines.
✅ Correct Answer: B. Work / Time
12. 1 Watt equals:
A watt (W) is the SI unit of power and represents the rate at which work is done or energy is transferred. One watt is defined as one joule of work done in one second. This unit is commonly used to express the power ratings of electrical appliances such as bulbs, fans, televisions, and motors. For example, a 100-watt bulb consumes electrical energy at the rate of 100 joules every second. Understanding the relationship between power, work, and time is essential for solving Physics problems and estimating energy consumption.
Key Points
- 1 Watt = 1 Joule per second (1 W = 1 J/s).
- Watt is the SI unit of power.
- It measures the rate of energy transfer.
- Electrical appliances are rated in watts.
- Named after James Watt.
✅ Correct Answer: A. 1 Joule per second
13. The unit used for electrical energy consumption in homes is:
The kilowatt-hour (kWh) is the commercial unit used to measure electrical energy consumed in homes and industries. Electricity supply companies use this unit to calculate monthly electricity bills because it is more convenient than using joules for large amounts of energy. One kilowatt-hour represents the energy consumed by a 1000-watt appliance operating for one hour. Although the SI unit of energy is the joule, the kilowatt-hour is widely used in practical applications related to electricity consumption.
Key Points
- Kilowatt-hour (kWh) is the commercial unit of electrical energy.
- 1 kWh = 1000 watt-hours.
- One unit of electricity equals 1 kWh.
- Electricity bills are based on kWh consumption.
- The SI unit of energy remains the joule (J).
✅ Correct Answer: C. Kilowatt-hour
14. A moving car possesses:
A moving car possesses kinetic energy because it is in motion. The amount of kinetic energy depends on the mass of the car and its speed. A heavier vehicle or one moving at a higher speed has greater kinetic energy. During braking, this kinetic energy is converted into heat due to friction between the brake pads and the wheels. Understanding kinetic energy helps explain why vehicles moving at high speeds require a longer distance to stop safely.
Key Points
- Moving objects possess kinetic energy.
- Kinetic energy depends on mass and speed.
- Higher speed means greater kinetic energy.
- Braking converts kinetic energy into heat energy.
- SI unit of kinetic energy is the joule (J).
✅ Correct Answer: B. Kinetic Energy
15. Water stored in a dam has:
Water stored in a dam possesses gravitational potential energy because it is stored at a height above the ground. When the water is released, this stored energy is converted into kinetic energy as it flows downward. In hydroelectric power plants, the moving water rotates turbines, which then drive generators to produce electricity. This is a practical example of energy transformation and demonstrates the importance of potential energy in generating renewable energy.
Key Points
- Water stored at a height has gravitational potential energy.
- Potential energy depends on mass and height.
- Flowing water converts potential energy into kinetic energy.
- Hydroelectric plants use this energy to generate electricity.
- Potential energy is measured in joules (J).
✅ Correct Answer: B. Potential Energy
16. The transformation of energy in a hydroelectric power plant is:
In a hydroelectric power plant, water stored at a height possesses gravitational potential energy. When the water is released, it flows downward and its potential energy is converted into kinetic energy. The moving water rotates the turbine, converting kinetic energy into mechanical energy. The generator connected to the turbine then converts this mechanical energy into electrical energy. Hydroelectric power is a renewable source of energy because it uses the natural flow of water without consuming fossil fuels.
Key Points
- Water stored in a dam has potential energy.
- Flowing water gains kinetic energy.
- The turbine converts kinetic energy into mechanical energy.
- The generator converts mechanical energy into electrical energy.
- Hydroelectric power is a renewable energy source.
✅ Correct Answer: B. Potential → Electrical
17. Energy cannot be created or destroyed. This law is called:
The Law of Conservation of Energy states that energy can neither be created nor destroyed, but it can be converted from one form to another. The total amount of energy in a closed system always remains constant. This principle explains many natural and everyday processes, such as the conversion of electrical energy into light and heat in a bulb, or potential energy into kinetic energy when an object falls. It is one of the most fundamental laws in Physics and forms the basis for understanding energy transformations.
Key Points
- Energy can neither be created nor destroyed.
- Energy can change from one form to another.
- Total energy remains constant in a closed system.
- It is called the Law of Conservation of Energy.
- The law applies to all physical processes.
✅ Correct Answer: B. Law of Conservation of Energy
18. The rate of doing work is called:
Power is the rate at which work is done or energy is transferred. It tells us how quickly a person or machine can complete a task. Two machines may perform the same amount of work, but the one that finishes in less time is considered more powerful. Power is calculated using the formula Power = Work ÷ Time and is measured in watts (W). Understanding power helps compare the efficiency and performance of machines, motors, and electrical appliances used in everyday life.
Key Points
- Power is the rate of doing work.
- Formula: P = W/t.
- SI unit of power is the watt (W).
- Higher power means work is completed faster.
- Power is used to compare the performance of machines.
✅ Correct Answer: C. Power
19. A machine that multiplies force is called:
A lever is one of the simplest machines used to multiply force and make work easier. It consists of a rigid bar that rotates around a fixed point called the fulcrum. Depending on the position of the fulcrum, load, and effort, a lever can either increase force or increase speed and distance. Everyday examples include a crowbar, seesaw, bottle opener, and wheelbarrow. Simple machines like levers help reduce human effort and improve efficiency in performing various tasks.
Key Points
- A lever is a simple machine.
- It works using a fulcrum, effort, and load.
- Levers help multiply force.
- Examples include crowbars and bottle openers.
- Simple machines make work easier and more efficient.
✅ Correct Answer: A. Lever
20. Mechanical energy is the sum of:
Mechanical energy is the total energy possessed by an object due to its motion and position. It is the sum of kinetic energy and potential energy. For example, a swinging pendulum continuously converts potential energy into kinetic energy and vice versa, but its total mechanical energy remains nearly constant if friction is neglected. Mechanical energy plays an important role in understanding the motion of vehicles, machines, falling objects, and many natural phenomena. It is measured in joules (J), the SI unit of energy.
Key Points
- Mechanical energy = Kinetic Energy + Potential Energy.
- It depends on both motion and position.
- Energy continuously transforms between kinetic and potential forms.
- Mechanical energy is measured in joules (J).
- The pendulum is a common example of mechanical energy transformation.
✅ Correct Answer: B. Kinetic + Potential Energy
Final Revision Tips
Before attempting the TNPSC Physics Work Energy Power Quiz, remember these key points:
• Work is done when force causes displacement.
• The SI unit of work and energy is Joule (J).
• Energy is the capacity to do work.
• Kinetic energy depends on mass and velocity.
• Potential energy depends on height and mass.
• Mechanical energy is the sum of kinetic and potential energy.
• Power is the rate of doing work.
• SI unit of power is Watt (W).
• Electrical energy consumption is measured in kilowatt-hour (kWh).
• Energy cannot be created or destroyed; it only changes form.
Further Reading
To strengthen your understanding of Work, Energy and Power, refer to the official NCERT Physics chapter on this topic. It explains the concepts of work, kinetic energy, potential energy, conservation of mechanical energy, and power with clear illustrations and examples. Revising these fundamentals will help build a strong conceptual base for TNPSC General Science preparation.
Official NCERT Textbook: Chapter 5 – Work, Energy and Power
