DELHI PUBLIC SCHOOL ONGC, NAZIRA
CLASS: IX A/B/C Date:
Name: Roll No.:
Subject: Science Assignment No.: 6, 2023-24 Max. Marks:
PHYSICS
Q1. Choose the correct option from the following :
(i). When a body rolls down an inclined plane, it has
(a) only kinetic energy (b) only potential energy
(c) both kinetic energy and potential energy (d) neither kinetic energy nor potential energy
(ii).Two bodies of equal weight are kept at heights of h and 1.5h respectively. The ratio of their potential energies is
(a) 3:2 (b) 2:3
(c) 1:1 (d) 4:3
(iii) Which one of the following is not the unit of energy?
(a) joule (b) newton metre
(c) kilowatt (d) kilowatt hour
Q2. For the given questions (i), (ii) and (iii) , two statements are given- one labeled Assertion (A) and the
other labeled Reason (R).
Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:
(a) Both A and R are true, and R is correct explanation of the assertion.
(b) Both A and R are true, but R is not the correct explanation of the assertion.
(c) A is true, but R is false.
(d) A is false, but R is true.
(i). Assertion: If momentum of a body is doubled, its kinetic energy becomes four fold.
Reason: Kinetic energy is proportional to square of momentum.
(ii) Assertion: The speed of the car is to be increased on approaching a hilly road.
Reason: To give more kinetic energy to it so that it moves up against gravity.
(iii) Assertion: Work done depends on angle between force and displacement.
Reason: Work done is a vector quantity.
Q3. Read the following paragraph and answer the questions:
When an object is allowed to fall from higher level to a lower level, it gains speed due to gravitational pull,
i.e, it gains kinetic energy. Therefore, in possessing height, a body has the ability to convert its height into
kinetic energy, i.e, it possesses potential energy.
The magnitude of its gravitational potential energy is equivalent to the amount of work done by the weight of
the body in causing the descent.
If a mass m is at a height h above a lower level, the potential energy possessed by the mass is mgh.
The chosen level from which height is measured has no absolute position. It is, therefore, important to indicate
clearly zero potential energy level in any problem in which potential energy is to be calculated. The potential
energy of the body may be positive or negative.
(a) Name the type of energy possessed by a compressed spring.
(b) A cement bag of mass 50kg has potential energy of 490J. To what height should it be raised?
(c) Establish the relationship between the commercial unit and SI unit of energy.
(d) The speed of a vehicle of mass 500kg increases from 36km/h to 72km/h. Calculate the increase in its kinetic
energy.
CLASS: IX A/B/C Date:
Name: Roll No.:
Subject: Science Assignment No.: 6, 2023-24 Max. Marks:
PHYSICS
Q1. Choose the correct option from the following :
(i). When a body rolls down an inclined plane, it has
(a) only kinetic energy (b) only potential energy
(c) both kinetic energy and potential energy (d) neither kinetic energy nor potential energy
(ii).Two bodies of equal weight are kept at heights of h and 1.5h respectively. The ratio of their potential energies is
(a) 3:2 (b) 2:3
(c) 1:1 (d) 4:3
(iii) Which one of the following is not the unit of energy?
(a) joule (b) newton metre
(c) kilowatt (d) kilowatt hour
Q2. For the given questions (i), (ii) and (iii) , two statements are given- one labeled Assertion (A) and the
other labeled Reason (R).
Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:
(a) Both A and R are true, and R is correct explanation of the assertion.
(b) Both A and R are true, but R is not the correct explanation of the assertion.
(c) A is true, but R is false.
(d) A is false, but R is true.
(i). Assertion: If momentum of a body is doubled, its kinetic energy becomes four fold.
Reason: Kinetic energy is proportional to square of momentum.
(ii) Assertion: The speed of the car is to be increased on approaching a hilly road.
Reason: To give more kinetic energy to it so that it moves up against gravity.
(iii) Assertion: Work done depends on angle between force and displacement.
Reason: Work done is a vector quantity.
Q3. Read the following paragraph and answer the questions:
When an object is allowed to fall from higher level to a lower level, it gains speed due to gravitational pull,
i.e, it gains kinetic energy. Therefore, in possessing height, a body has the ability to convert its height into
kinetic energy, i.e, it possesses potential energy.
The magnitude of its gravitational potential energy is equivalent to the amount of work done by the weight of
the body in causing the descent.
If a mass m is at a height h above a lower level, the potential energy possessed by the mass is mgh.
The chosen level from which height is measured has no absolute position. It is, therefore, important to indicate
clearly zero potential energy level in any problem in which potential energy is to be calculated. The potential
energy of the body may be positive or negative.
(a) Name the type of energy possessed by a compressed spring.
(b) A cement bag of mass 50kg has potential energy of 490J. To what height should it be raised?
(c) Establish the relationship between the commercial unit and SI unit of energy.
(d) The speed of a vehicle of mass 500kg increases from 36km/h to 72km/h. Calculate the increase in its kinetic
energy.
