Questions & Answers HS (11th & 12th) : MCQ Physics Chapter 6: WORK, ENERGY AND POWER, HS 1st year

MCQs

What is the scalar product (dot product) of two vectors $\mathbf{A}$ and $\mathbf{B}$ ?
- A) $\mathbf{A} \cdot \mathbf{B} = AB \sin \theta$
- B) $\mathbf{A} \cdot \mathbf{B} = AB \cos \theta$
- C) $\mathbf{A} \cdot \mathbf{B} = AB \tan \theta$
- D) $\mathbf{A} \cdot \mathbf{B} = AB / \cos \theta$
Answer: B) $\mathbf{A} \cdot \mathbf{B} = AB \cos \theta$
In physics, when is the work done by a force equal to zero?
- A) When there is no displacement.
- B) When the force is perpendicular to the displacement.
- C) When the force is zero.
- D) All of the above.
Answer: D) All of the above.
The work-energy theorem states:
- A) The change in potential energy is equal to the work done by net force.
- B) The change in kinetic energy is equal to the work done by net force.
- C) The work done by a force is equal to the product of force and acceleration.
- D) Energy is always conserved in a closed system.
Answer: B) The change in kinetic energy is equal to the work done by net force.
Which of the following quantities is a scalar?
- A) Force
- B) Displacement
- C) Work
- D) Velocity
Answer: C) Work
For a spring with spring constant $k$ , the potential energy stored in the spring when compressed or stretched by $x$ is given by:
- A) $V(x) = \frac{1}{2} k x^2$
- B) $V(x) = kx$
- C) $V(x) = \frac{1}{2} m v^2$
- D) $V(x) = kx^3$
Answer: A) $V(x) = \frac{1}{2} k x^2$
The SI unit of power is:
- A) Joule
- B) Watt
- C) Horsepower
- D) Newton
Answer: B) Watt
In an elastic collision:
- A) Only momentum is conserved.
- B) Only kinetic energy is conserved.
- C) Both momentum and kinetic energy are conserved.
- D) Neither momentum nor kinetic energy is conserved.
Answer: C) Both momentum and kinetic energy are conserved.
What is the power delivered by a force $\mathbf{F}$ acting on a body moving with velocity $\mathbf{v}$ ?
- A) $P = \mathbf{F} \cdot \mathbf{v}$
- B) $P = Fv \sin \theta$
- C) $P = Fv^2$
- D) $P = F/v$
Answer: A) $P = \mathbf{F} \cdot \mathbf{v}$

What is the dimensional formula for work and energy?
- A) $[M^1 L^2 T^{-3}]$
- B) $[M^1 L^1 T^{-2}]$
- C) $[M^1 L^2 T^{-2}]$
- D) $[M^2 L^1 T^{-2}]$
Answer: C) $[M^1 L^2 T^{-2}]$

What is the work done by a conservative force in a closed path?
- A) Positive
- B) Negative
- C) Zero
- D) Depends on the path
Answer: C) Zero

Which of the following is an example of a non-conservative force?
- A) Gravitational force
- B) Spring force
- C) Frictional force
- D) Electrostatic force
Answer: C) Frictional force

In a one-dimensional elastic collision between two particles of equal mass, the velocities after collision are such that:
- A) Both particles come to rest.
- B) Both particles exchange their velocities.
- C) Both particles move with half of their initial velocities.
- D) Both particles move with twice their initial velocities.
Answer: B) Both particles exchange their velocities.

The principle of conservation of mechanical energy is valid if:
- A) Only conservative forces are acting.
- B) Non-conservative forces are acting.
- C) Both conservative and non-conservative forces are acting.
- D) There is no force acting on the body.
Answer: A) Only conservative forces are acting.

If the potential energy of a body is given by $V(x) = kx^2/2$ , what is the force acting on the body?
- A) $F = kx$
- B) $F = -kx$
- C) $F = kx^2$
- D) $F = -kx^2$
Answer: B) $F = -kx$

The power output of a machine is defined as:
- A) Work done by the machine.
- B) Work done by the machine per unit time.
- C) Energy consumption by the machine.
- D) Force applied by the machine per unit time.
Answer: B) Work done by the machine per unit time.

The kinetic energy of a body of mass $m$ moving with velocity $v$ is given by:
- A) $mv$
- B) $\frac{1}{2} mv^2$
- C) $mv^2$
- D) $\frac{1}{2} mv$
Answer: B) $\frac{1}{2} mv^2$

Which of the following conditions must be true for work to be done by a force?
- A) The force must be perpendicular to the displacement.
- B) There must be displacement in the direction of the force.
- C) There must be a potential energy change.
- D) The force must be constant.
Answer: B) There must be displacement in the direction of the force.

For a particle of mass $m$ moving under the influence of gravity, the potential energy at height $h$ is given by:
- A) $V = \frac{1}{2} mgh$
- B) $V = mgh$
- C) $V = mg/h$
- D) $V = \frac{1}{2} mgh^2$
Answer: B) $V = mgh$

The work-energy theorem states that the net work done on a particle is equal to:
- A) The change in its potential energy.
- B) The change in its total energy.
- C) The change in its kinetic energy.
- D) The change in its velocity.
Answer: C) The change in its kinetic energy.

What happens to the speed of a satellite as it moves closer to Earth in its orbit, assuming negligible atmospheric resistance?
- A) The speed decreases due to loss of energy.
- B) The speed increases due to conservation of angular momentum.
- C) The speed remains constant.
- D) The speed decreases due to gravitational pull.
Answer: B) The speed increases due to conservation of angular momentum.

Which of the following represents the SI unit of power?
- A) Joule-second
- B) Watt-second
- C) Watt
- D) Newton-meter
Answer: C) Watt

In a variable force scenario, the work done is computed using:
- A) $W = F \cdot d$
- B) $W = \int F dx$
- C) $W = F \cdot v$
- D) $W = \frac{1}{2} F \cdot d$
Answer: B) $W = \int F dx$

What is the potential energy of a spring stretched or compressed by a distance $x$ ?
- A) $V = kx$
- B) $V = kx^2$
- C) $V = \frac{1}{2}kx^2$
- D) $V = \frac{1}{3}kx^3$
Answer: C) $V = \frac{1}{2}kx^2$

In an inelastic collision:
- A) Momentum is conserved, but kinetic energy is not.
- B) Kinetic energy is conserved, but momentum is not.
- C) Both momentum and kinetic energy are conserved.
- D) Neither momentum nor kinetic energy is conserved.
Answer: A) Momentum is conserved, but kinetic energy is not.

If a block of mass $m$ moves with constant velocity $v$ over a rough surface under a pulling force $F$ , the work done by friction is:
- A) Positive and equal to $Fd$ .
- B) Negative and equal to $-Fd$ .
- C) Zero.
- D) Depends on the coefficient of friction.
Answer: B) Negative and equal to $-Fd$ .

The power delivered by a force acting on a particle moving with instantaneous velocity $\mathbf{v}$ is given by:
- A) $P = F \cdot v$
- B) $P = Fv^2$
- C) $P = F \times v$
- D) $P = Fv \sin \theta$
Answer: A) $P = F \cdot v$

The potential energy of a particle moving under a conservative force is related to the force by:
- A) $F = -\frac{dV}{dx}$
- B) $F = \frac{d^2V}{dx^2}$
- C) $F = \frac{dV}{dx}$
- D) $F = -\frac{d^2V}{dx^2}$
Answer: A) $F = -\frac{dV}{dx}$

A constant force of 10 N is applied to a body moving in the direction of the force over a displacement of 5 m. The work done is:
- A) 5 J
- B) 10 J
- C) 50 J
- D) 500 J
Answer: C) 50 J

In a system with only conservative forces acting, the sum of kinetic energy and potential energy is:
- A) Constant.
- B) Zero.
- C) Equal to work done.
- D) Always decreasing.
Answer: A) Constant.

The unit of the spring constant $k$ is:
- A) Newton-meter ( $\text{N·m}$ )
- B) Joule ( $\text{J}$ )
- C) Newton per meter ( $\text{N/m}$ )
- D) Pascal ( $\text{Pa}$ )
Answer: C) Newton per meter ( $\text{N/m}$ )

In an elastic collision in one dimension, if a body of mass $m_1$ collides with another body of mass $m_2$ at rest, the velocity of $m_1$ after the collision is given by:
- A) $v_{1f} = \frac{m_1 - m_2}{m_1 + m_2} v_{1i}$
- B) $v_{1f} = \frac{2m_1}{m_1 + m_2} v_{1i}$
- C) $v_{1f} = \frac{2m_2}{m_1 + m_2} v_{1i}$
- D) $v_{1f} = \frac{m_1 + m_2}{m_1 - m_2} v_{1i}$
Answer: A) $v_{1f} = \frac{m_1 - m_2}{m_1 + m_2} v_{1i}$

The potential energy of a body subjected to gravity at height $h$ above the ground is:
- A) Directly proportional to $h^2$ .
- B) Directly proportional to $h$ .
- C) Inversely proportional to $h$ .
- D) Independent of $h$ .
Answer: B) Directly proportional to $h$ .

In the case of a perfectly inelastic collision, which of the following quantities is conserved?
- A) Kinetic energy only.
- B) Momentum only.
- C) Both momentum and kinetic energy.
- D) Neither momentum nor kinetic energy.
Answer: B) Momentum only.

The work done by a force $\mathbf{F}$ acting on a particle moving with displacement $\mathbf{d}$ is maximum when:
- A) $\mathbf{F}$ is perpendicular to $\mathbf{d}$ .
- B) $\mathbf{F}$ is parallel to $\mathbf{d}$ .
- C) $\mathbf{F}$ is opposite to $\mathbf{d}$ .
- D) The angle between $\mathbf{F}$ and $\mathbf{d}$ is $90^\circ$ .
Answer: B) $\mathbf{F}$ is parallel to $\mathbf{d}$ .

The gravitational potential energy at a height $h$ above the surface of Earth, considering the variation of gravity, is given by:
- A) $V = -\frac{G M_E m}{h}$
- B) $V = -\frac{G M_E m}{R_E}$
- C) $V = -\frac{G M_E m}{R_E + h}$
- D) $V = \frac{G M_E m}{R_E + h}$
Answer: C) $V = -\frac{G M_E m}{R_E + h}$

When a spring is stretched or compressed by $x$ , the restoring force is proportional to $x$ . This law is known as:
- A) Coulomb's Law.
- B) Hooke's Law.
- C) Newton's Third Law.
- D) Bernoulli's Principle.
Answer: B) Hooke's Law.

In which of the following scenarios is mechanical energy not conserved?
- A) A block sliding on a frictionless inclined plane.
- B) A pendulum oscillating without air resistance.
- C) A freely falling object under gravity.
- D) A block sliding on a rough surface.
Answer: D) A block sliding on a rough surface.

The unit of work in the CGS system is:
- A) Joule
- B) Dyne
- C) Erg
- D) Newton
Answer: C) Erg

If a force acts on an object at an angle $\theta$ to its displacement, the work done is given by:
- A) $W = Fd \sin \theta$
- B) $W = Fd \cos \theta$
- C) $W = Fd \tan \theta$
- D) $W = Fd / \cos \theta$
Answer: B) $W = Fd \cos \theta$

The kinetic energy of a particle is doubled. What happens to its momentum?
- A) It remains the same.
- B) It becomes double.
- C) It becomes $\sqrt{2}$ times.
- D) It becomes four times.
Answer: C) It becomes $\sqrt{2}$ times.

The power of a motor lifting a mass $m$ vertically with velocity $v$ is:
- A) $P = mv^2$
- B) $P = mgh$
- C) $P = mgv$
- D) $P = mgh/v$
Answer: C) $P = mgv$

The work done by friction is always:
- A) Positive.
- B) Negative.
- C) Zero.
- D) Dependent on the situation.
Answer: B) Negative.

If a particle moves in a circular path under a central force, the work done by the force over one complete revolution is:
- A) Positive.
- B) Negative.
- C) Zero.
- D) Depends on the radius of the circle.
Answer: C) Zero.

The instantaneous power delivered by a constant force is given by:
- A) $P = Fv^2$
- B) $P = Fv \cos \theta$
- C) $P = Fv \sin \theta$
- D) $P = Fd \cos \theta$
Answer: B) $P = Fv \cos \theta$

MCQ Physics for Class 11 with Answers: Boost Your Preparation

Looking for MCQ Physics for Class 11 with answers? You’ve come to the right place! Mastering multiple-choice questions is essential for acing your exams and strengthening your understanding of physics concepts. Here, we provide a comprehensive collection of MCQs from various chapters in Class 11 Physics, designed to help students practice effectively and excel in their studies.

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Class 11 Physics MCQ Topics Covered

We’ve curated MCQs from the following critical chapters in the Class 11 Physics syllabus:

Physical World and Measurement
- Example:
  Q: Which of the following is a fundamental unit in physics?
  a) Newton
  b) Kilogram
  c) Joule
  d) Watt
  Answer: b) Kilogram
Kinematics
- Example:
  Q: A particle moves in a straight line with uniform acceleration. If its initial velocity is 5 m/s, acceleration is 2 m/s², and time is 3 seconds, what is the final velocity?
  a) 5 m/s
  b) 11 m/s
  c) 10 m/s
  d) 20 m/s
  Answer: d) 20 m/s
Laws of Motion
- Example:
  Q: Newton’s first law is also known as:
  a) Law of Acceleration
  b) Law of Inertia
  c) Law of Gravitation
  d) None of these
  Answer: b) Law of Inertia
Work, Energy, and Power
- Example:
  Q: The work done by a force is zero when the angle between force and displacement is:
  a) 0°
  b) 45°
  c) 90°
  d) 180°
  Answer: c) 90°
Gravitation
- Example:
  Q: The value of acceleration due to gravity on the surface of Earth is approximately:
  a) 8.9 m/s²
  b) 9.8 m/s²
  c) 10.8 m/s²
  d) 11.8 m/s²
  Answer: b) 9.8 m/s²

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Pro Tips for Solving Physics MCQs

Read the Question Carefully: Avoid making assumptions before fully reading.
Practice Regularly: Consistency is key to mastering Physics MCQs.
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FAQs

Are these MCQs suitable for NEET or JEE aspirants?
Yes, they are tailored to align with the syllabus of major competitive exams.
Where can I download PDF versions?
Stay tuned! A downloadable PDF link will be available soon.

Happy Learning! 🚀

Questions & Answers HS (11th & 12th)

Sunday, November 17, 2024

MCQ Physics Chapter 6: WORK, ENERGY AND POWER, HS 1st year

MCQs

MCQ Physics for Class 11 with Answers: Boost Your Preparation

Why Are MCQs Important in Physics?

Class 11 Physics MCQ Topics Covered

Benefits of Practicing Class 11 Physics MCQs

Pro Tips for Solving Physics MCQs

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