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Consider this, riding a bicycle uphill, carrying your school encapsulated in a bag, and even running a race; every one of these actions involves work and energy. Now, whether you are moving an object or accelerating, all these day-to-day activities relate to concepts explained in Chapter 11 – Work, Energy, and Power from the Class 9 Science NCERT Exemplar.
The NCERT exemplar solutions for this chapter has been crafted with utmost precision by professionals in the field. They intend to facilitate learning by offering comprehensive, methodical answers to every single problem. Every answer is provided in a systematic manner which enables students to deepen their understanding of the basics.
Moreover, these Class 9 Science NCERT Exemplar Solutions are highly reliable and accurate in accordance with the current syllabus of CBSE Class 9 Science. They prepare the students well for the examinations while providing an in-depth understanding of the concepts.
When a body falls freely towards the earth, then its total energy
(a) increases
(b) decreases
(c) remains constant
(d) first increases and then decreases
Question:2
A car is accelerated on a levelled road and attains a velocity 4 times of its initial velocity. In this process the potential energy of the car
(a) does not change
(b) becomes twice to that of initial
(c) becomes 4 times that of initial
(d) becomes 16 times that of initial
Question:3
In case of negative work the angle between the force and displacement is
(a)
Question:4
An iron sphere of mass 10 kg has the same diameter as an aluminium sphere of mass is 3.5 kg. Both spheres are dropped simultaneously from a tower. When they are 10 m above the ground, they have the same
(a) acceleration
(b) momenta
(c) potential energy
(d) Kinetic energy
Question:5
A girl is carrying a school bag of 3 kg mass on her back and moves 200 m on a levelled road. The work done against the gravitational force will be
(a)
(b)
(c)
(d) zero
Question:6
Which one of the following is not the unit of energy?
(a) joule
(b) newton metre
(c) kilowatt
(d) kilowatt hour
Question:7
The work done on an object does not depend upon the
(a) displacement
(b) force applied
(c) angle between force and displacement
(d) initial velocity of the object
Question:8
Water stored in a dam possesses
(a) no energy
(b) electrical energy
(c) kinetic energy
(d) potential energy
Answer:
Answer: [D]Question:9
A body is falling from a height h. After it has fallen a height h/2, it will possess
(a) only potential energy
(b) only kinetic energy
(c) half potential and half kinetic energy
(d) more kinetic and less potential energy
Answer:
Answer: [C]Question:10
Answer:
Solution.Question:11
Answer:
Solution.Question:12
A boy is moving on a straight road against a frictional force of 5 N. After travelling a distance of 1.5 km he forgot the correct path at a round-about of radius 100 m. However, he moves on the circular path for one and half cycle and then he moves forward upto
Answer:
Answer:Question:13
Can any object have mechanical energy even if its momentum is zero? Explain.
Answer:
Solution.Question:14
Can any object have mechanical energy even if its momentum is zero? Explain.
Answer:
Solution.Question:15
The power of a motor pump is 2 kW. How much water per minute the pump can raise to a height of 10 m? (Given
Answer:
Question:16
Answer:
Answer:Question:17
Answer:
Solution.Question:18
Answer:
Solution.Question:19
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Solution.Question:20
Answer:
Answer:Answer:
Solution.Question:22
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Solution.Question:23
A girl having mass of 35 kg sits on a trolley of mass 5 kg. The trolley is given an initial velocity of
The trolley comes to rest after traversing a distance of 16 m.
(a) How much work is done on the trolley?
(b) How much work is done by the girl?
Answer:
Solution
Question:24
Answer:
Solution.Question:25
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SolutionQuestion:26
Answer:
Power of anything is defined as the rate of work done by that thing or energy supplied per unit time.Question:27
Answer:
Solution.Question:28
Compare the power at which each of the following is moving upwards against the force of gravity?
(i) a butterfly of mass
(ii) a 250 g squirrel climbing up on a tree at a rate of
Answer:
Solution.
Chapter wise solutions |
Concept Clarity - As in work, energy, power, and mechanical energy, these concepts are deeply explained in very simple words.
Step-by-Step Solutions - Each practical and theoretical question is solved in a specific manner so that strong problem-solving abilities can be developed.
Based on CBSE Syllabus - Completely integrated with the most recent Class 9 CBSE Science syllabus.
Covers All Question Formats - Contains MCQs, short answer questions, long answer questions, and questions that require application of concepts.
Focus on Real-Life Applications - Concept of energy conversion, machines, and power is explained with the help of relevant examples.
Clear Mathematical Derivations - Important derivations such as Work-Energy Theorem and power and energy formulas are included.
Also, read - NCERT Solutions for Class 9
Chapter No. | Chapter Name |
Chapter 1 | Matter in Our Surroundings |
Chapter 2 | Is Matter Around Us Pure |
Chapter 3 | Atoms and Molecules |
Chapter 4 | Structure of The Atom |
Chapter 5 | The Fundamental Unit of Life |
Chapter 6 | Tissues |
Chapter 7 | Diversity in Living Organisms |
Chapter 8 | Motion |
Chapter 9 | Force and Laws of Motion |
Chapter 10 | Gravitation |
Chapter 11 | Work and Energy |
Chapter 12 | Sound |
Chapter 13 | Why Do We Fall ill? |
Chapter 14 | Natural Resources |
Chapter 15 | Improvement in Food Resources |
Work is said to be done when a force is applied on an object and the object moves in the direction of the force.
Average power is total work done divided by total time, while instantaneous power is power at a specific moment in time.
Energy is required for every activity—from walking and cooking to running machines and lighting homes.
No, according to the law of conservation of energy, it can only be transformed from one form to another.
Because joules are very small units; kilowatt-hours are more practical for measuring large-scale energy consumption.
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