Every question from this NCERT chapter, with a detailed explanation.
With reference to the commercial unit of energy, consider the following statements: 1. The commercial unit of energy is expressed simply as kilowatt (kW). 2. It is used because the Joule is a very small unit for large energy quantities. 3. One unit in electricity bills represents one kilowatt-hour. Which of the statements given above are correct?
Consider the following statements regarding the unit of work: 1. The SI unit of work is the Joule (J). 2. One Joule is the work done when a force of 1 Newton moves an object by 1 centimetre in the direction of the force. 3. The unit of work is the same as the unit of energy. Which of the statements given above are correct?
In which of the following scenarios is the work done by the force considered negative?
When an object is lifted vertically upwards, the work done by the gravitational force is:
Why is the work done by the gravitational force on a satellite moving in a circular orbit around the Earth considered to be zero?
With reference to the formula $W = F \times s$, consider the following statements: 1. This formula applies when the force is constant. 2. This formula applies when the force acts perpendicular to the direction of displacement. 3. If displacement is in the opposite direction to force, the formula becomes $W = -F \times s$. Which of the statements given above are correct?
What does the term 'Power' refer to in physics?
Consider the following statements regarding Power: 1. Power is a scalar quantity. 2. The power of a machine is independent of the time taken to complete a task. 3. One kilowatt is equal to 1000 Joules per second. Which of the statements given above are correct?
Match List I with List II and select the correct answer using the code given below: List I | List II A. Work | 1. Newton ($N$) B. Power | 2. Joule ($J$) C. Energy | 3. Newton-metre ($N\ m$) D. Force | 4. Watt ($W$)
Which of the following correctly explains why a more powerful engine can accelerate a car faster?
A porter lifts a luggage of 15 kg from the ground and puts it on his head. Which of the following statements correctly describes the work done in this process?
With reference to the scientific concept of 'work', consider the following statements: 1. Work is said to be done only when a force acts on an object and the object is displaced. 2. If a person pushes a huge rock hard but it does not move, scientific work is considered to be done due to the exhaustion of energy. 3. Mental labour, such as reading or thinking, does not constitute work in science. Which of the statements given above is/are correct?
Consider the following situations: 1. A girl pulls a trolley but it does not move. 2. A person lifts a heavy load from the ground to their head. 3. A satellite moves from a lower orbit to a higher orbit. In which of the above situations is 'work' said to be done according to the scientific definition?
Which one of the following best defines the quantity of work done by a constant force?
With reference to the nature of work done, consider the following statements: 1. Work done is negative when the force acts in the direction of displacement. 2. Work done is negative when the force acts opposite to the direction of displacement. 3. Work done is maximum when the force acts perpendicular to the displacement. Which of the statements given above is/are correct?
With reference to 'Work', consider the following statements: 1. Work is a vector quantity having both magnitude and direction. 2. If the displacement of an object is zero, the work done by any force acting on it is zero. 3. Work done by gravity on an object moving horizontally is zero. Which of the statements given above is/are correct?
Which of the following pairs is correctly matched regarding the nature of work done? Pair | Situation | Nature of Work 1 | Gravity acting on a freely falling body | Positive 2 | Friction acting on a moving block | Positive 3 | Lifting a bucket from a well (work by applied force) | Negative 4 | Moon orbiting the Earth (work by Earth's gravity) | Positive
Consider an object moving with a uniform velocity. If a force is applied in the direction opposite to its motion, what happens to the work done by this force?
According to the scientific definition of work, what is the magnitude of work done on an object if the force acting on it is zero?
Which one of the following is the correct relationship between the commercial unit of energy (kWh) and the SI unit of energy (Joule)?
With reference to Kinetic Energy (KE), consider the following statements: 1. It is the energy possessed by an object by virtue of its position. 2. The kinetic energy of an object is directly proportional to its mass. 3. The kinetic energy of an object is directly proportional to the square of its velocity. Which of the statements given above is/are correct?
If the velocity of a moving object is doubled, its kinetic energy will:
Consider the following examples: 1. A falling coconut. 2. A speeding car. 3. Blowing wind. 4. A compressed spring. Which of the above possess Kinetic Energy?
Consider an object raised to a height $h$. The gravitational potential energy gained by the object depends on: 1. The volume of the object. 2. The height to which it is raised. 3. The acceleration due to gravity at that place. Which of the statements given above is/are correct?
The work done on an object to change its velocity from $u$ to $v$ is equal to:
Which of the following statements regarding Energy is correct?
How is the kinetic energy of a moving body defined quantitatively?
A car and a truck are moving with the same velocity. If the truck is four times as massive as the car, how does the kinetic energy of the truck compare to that of the car?
An object is lifted from point A to point B via three different paths: vertically, along a zigzag path, and along a ramp. Which of the following statements is correct regarding the work done by gravity?
Consider the following objects/activities: 1. A bullet piercing a target. 2. A stretched bow. 3. A compressed spring. Which of the above possess Kinetic Energy?
If the speed of a car is increased from 30 km/h to 60 km/h, the work done on the car is proportional to:
With reference to Potential Energy (PE), consider the following statements: 1. It is the energy possessed by an object by virtue of its position or configuration. 2. A speeding car possesses potential energy. 3. The potential energy of an object at a height depends on the acceleration due to gravity. Which of the statements given above is/are correct?
The energy stored in a wound-up spring of a toy car is an example of:
Which one of the following energy transformations primarily occurs when an arrow is released from a stretched bow?
The gravitational potential energy of an object at a height is defined as:
Which of the following objects possesses energy due to its configuration (change in shape)?
If the acceleration due to gravity ($g$) is considered constant, the potential energy of an object is directly proportional to:
The potential energy of an object at a given height is dependent on the chosen zero level. This implies that potential energy is:
If an object is lifted to a height $2h$ instead of $h$ above the ground, how does its gravitational potential energy change?
In the context of hydroelectric power generation, water stored in a dam possesses which form of energy?
A bamboo stick bent into the shape of a bow possesses potential energy primarily due to:
What is the minimum magnitude of force required to lift an object of mass $m$ vertically upwards at a constant velocity?
Which one of the following statements correctly describes the energy changes of an object falling freely from a height?
At any point during the free fall of an object (ignoring air resistance), the sum of its potential energy and kinetic energy is:
With reference to a simple pendulum oscillating, consider the following statements: 1. It illustrates the law of conservation of energy. 2. At the extreme positions, the kinetic energy is maximum. 3. At the mean position, the potential energy is maximum. Which of the statements given above is/are correct?
When an object dropped from a height is at the instant just before impact with the ground, which of the following is correct?
In the absence of air resistance, the loss in gravitational potential energy of a freely falling body is transformed into:
Which one of the following pairs of devices and energy transformations is NOT correctly matched?
When an object is dropped from a certain height, what form of energy does it possess at the midpoint of its fall?
What happens to the kinetic energy of an object if the net work done on it is negative?
For a freely falling body, the graph representing Total Energy versus Height is:
Which one of the following correctly defines the unit 'Watt'?
Two individuals of equal weight climb to the same height, but one takes less time than the other. Which of the following statements is correct?
Which one of the following is a unit of measurement for Energy?
The concept of 'Average Power' is primarily applicable in situations where:
What does the commercial unit of energy, 'kilowatt-hour' (kWh), represent?
If the mass of a moving object is doubled and its velocity is halved, how is its kinetic energy affected?
If an object moves in a direction perpendicular to the line of action of an applied force, the power expended by that force is:
For an object moving with velocity $v$ under the action of a constant force $F$ in the direction of motion, the power $P$ is given by:
Consider the following statements: 1. A bullock pulling a cart performs work. 2. A man pushing a stationary wall performs work. 3. A satellite revolving in a circular orbit performs work. Which of the above represent valid examples of work done in science?