NCERT  ·  Physics  ·  Class XI  ·  Ch.5

Work, Energy and Power
MCQ Master Series

Work · Kinetic & Potential Energy · Work–Energy Theorem · Power

🎯 50 Questions
⏱ 45 min Suggested
📊 3 Tiers
🗂 6 Topics
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Question Intelligence

Quiz Analytics

A data-driven breakdown of all 50 questions by difficulty, exam origin and topic distribution.

📈 Distribution Overview

50
Total Questions
Concept Check (NCERT)
26
Boards / JEE Main
16
JEE/NEET Edge Cases
8

🗂 Topic Coverage

Work & Work by Forces
20%
Kinetic Energy & W–K Theorem
20%
Potential Energy & Conservation
20%
Power & Efficiency
16%
Variable Forces & Graphs
12%
Mixed Concept Applications
12%
26
Concept Check (NCERT)
16
Boards / JEE Main
8
JEE/NEET Edge Cases
Conceptual Framework

Key Concept Highlights

6 foundational pillars that power every question in this quiz. Understand these, and the answers follow naturally.

🧱
Work Done by a Force
Work measures energy transfer when a force causes displacement, and for a constant force equals the product of force, displacement and the cosine of the angle between them.
🚀
Kinetic Energy & Work–Energy Theorem
Kinetic energy is the energy of motion; the work–energy theorem states that the net work done on a particle equals the change in its kinetic energy.
🏔️
Potential Energy & Conservative Forces
Potential energy is stored energy associated with configuration in a conservative force field, and changes in it relate to work done by conservative forces.
♻️
Conservation of Mechanical Energy
In the absence of non-conservative work, the sum of kinetic and potential energies of a system remains constant during its motion.
⚡
Power & Rate of Doing Work
Power quantifies how fast work is done or energy is transferred, and can be expressed as the product of force and velocity at an instant.
📈
Work from Force–Displacement Graphs
For variable forces, work done is obtained from the area under the force–displacement curve, linking graphical analysis with energy concepts.
Pedagogical Value

Why MCQs Matter

Multiple-choice questions are not mere guessing games — they are the sharpest diagnostic tool available to a competitive exam aspirant.

~4–6%

of Class XI Mechanics weightage across Boards & JEE/NEET (via work–energy theorem, potential energy curves & power calculations).

Quick Reference

Important Formula Capsules

10 must-memorise equations that surface repeatedly across CBSE and JEE papers.

Work (constant force)
\[ W = \vec{F} \cdot \vec{s} = Fs\cos\theta \]
Work (variable force)
\[ W = \int_{s_1}^{s_2} \vec{F} \cdot d\vec{s} \]
Kinetic Energy
\[ K = \dfrac{1}{2} m v^{2} \]
Work–Energy Theorem
\[ W_{\text{net}} = \Delta K \]
Gravitational Potential E.
\[ U = mgh \]
Change in Potential E.
\[ \Delta U = -W_{\text{cons}} \]
Mechanical Energy
\[ E_{\text{mech}} = K + U \]
Conservation of E.
\[ K_1 + U_1 = K_2 + U_2 \]
Average Power
\[ P_{\text{avg}} = \dfrac{W}{\Delta t} \]
Instantaneous Power
\[ P = \vec{F} \cdot \vec{v} \]
Learning Outcomes

What You Will Learn

By completing this quiz set you will have exercised all the following competencies.

01 Define work, identify when work is positive, negative or zero, and calculate work done by constant and simple variable forces in one dimension.
02 State and apply the work–energy theorem to relate net work with change in kinetic energy in translational motion scenarios.
03 Distinguish between kinetic and potential energy, and compute gravitational potential energy changes near Earth’s surface and in simple systems like springs.
04 Use conservation of mechanical energy to solve problems involving free fall, smooth inclines, pendulum-like motion and simple projectile situations.
05 Define power, differentiate between average and instantaneous power, and calculate power in mechanical systems using P = W/Δt and P = F·v.
06 Interpret and use force–displacement graphs to obtain work done as area under the curve for basic variable-force problems.
07 Analyse everyday situations such as lifting objects, braking vehicles, walking upstairs and machine ratings using work, energy, power and efficiency ideas.
Exam Preparation

Strategy & Preparation Tips

5 evidence-based strategies to maximise your score in CBSE Boards and JEE.

Step 01
Master Work Basics & Sign
Start with definitions of work, unit and sign conventions; practise questions on work done by constant forces at different angles to avoid plus–minus confusion in MCQs.
Step 02
Use Work–Energy as a Tool
Prefer the work–energy theorem over full kinematics when only speeds and displacements are involved; it cuts algebra and is heavily tested in Boards and JEE Main.
Step 03
Track K, U and Emech
Write K + U at initial and final positions, cancel common terms and solve; sketch energy bar diagrams to visualise conservation versus loss due to friction.
Step 04
Relate Power to F·v
Practise converting between work-per-time and force–velocity forms of power, and connect them to numerical ratings of engines, motors and human power output.
Step 05
Graph Sense for Variable F
Train yourself to read force–displacement graphs and quickly estimate work from the enclosed area; many tricky objective questions are just area-calculation in disguise.

Ready to Test Your Mastery?

50 questions  ·  Elapsed timer  ·  Instant scored results

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🎯 Knowledge Check

Physics — WORK, ENERGY AND POWER

50 Questions Class 11 MCQs
1
What is the SI unit of work?
2
Work done is zero when the angle between force and displacement is:
3
Which of the following is a scalar quantity?
4
A force acts on a body but causes no displacement. The work done is:
5
The kinetic energy of a body depends on:
6
The work done by centripetal force in circular motion is:
7
Which force is non-conservative?
8
The dimensional formula of energy is:
9
Which of the following is a unit of power?
10
A body moving with constant velocity has:
11
The work–energy theorem states that:
12
If velocity of a body is doubled, its kinetic energy becomes:
13
Gravitational potential energy depends on:
14
Which of the following has maximum kinetic energy?
15
The unit of horsepower is:
16
The potential energy of a stretched spring is:
17
Mechanical energy is conserved when:
18
The commercial unit of electrical energy is:
19
Efficiency of a machine is always:
20
Power is defined as:
21
A body of mass \(m\) is moving with speed \(v\). Its kinetic energy is:
22
A body falls freely under gravity. Which quantity remains constant?
23
If work done on a body is negative, then its kinetic energy:
24
The slope of force–displacement graph gives:
25
The area under force–displacement graph represents:
26
A ball thrown vertically upward reaches maximum height when:
27
The unit joule is equivalent to:
28
Instantaneous power is given by:
29
A body slides on a rough surface. Mechanical energy:
30
Which graph gives work directly?
31
The work done by gravity in upward motion is:
32
Power required to lift a body vertically depends on:
33
A bullet embeds in a block. Mechanical energy is:
34
A machine has efficiency 80%. This means:
35
The work done by friction is always:
36
A body of mass \(2\,kg\) moving at \(3\,m/s\) has kinetic energy:
37
The work done by spring force when stretched is:
38
In an ideal machine, efficiency is:
39
A body thrown upward returns with:
40
Which quantity changes fastest with velocity?
41
The stopping distance of a vehicle depends on:
42
If work done is independent of path, the force is:
43
The dot product \( \vec{F}\cdot\vec{s} \) represents:
44
A block slides down a rough incline. Mechanical energy:
45
A car moving at high speed is stopped by brakes. KE converts into:
46
Power of an engine is best measured in:
47
For maximum work done, the angle between force and displacement should be:
48
Which situation involves zero work?
49
Energy of a moving body is doubled if:
50
The most suitable method to find velocity without time is:
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Frequently Asked Questions

Work is said to be done when a force produces displacement in the direction of the force.

Work = Force × Displacement × cos?

Because it has magnitude only and no direction.

Work is positive when force and displacement are in the same direction.

Work is negative when force acts opposite to displacement.

Work is zero when displacement is zero or force is perpendicular to displacement.

Centripetal force in uniform circular motion does zero work.

A force whose magnitude or direction changes with displacement.

By finding the area under the force–displacement graph.

Energy is the capacity to do work.

Joule (J).

The sum of kinetic energy and potential energy.

Energy possessed by a body due to its motion.

KE = ½ mv²

Mass of the body and square of its velocity.

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