# WBJEE: Important Questions and Preparation Tips – Gravitation

The chapter Gravitation plays an important role in WBJEE Examination. If you have gone through each chapter thoroughly, then you do not need to revise the complete chapters just before few days of the examination. Instead of revising complete chapter you can revise chapter notes given in this article.

Created On: Oct 12, 2017 14:10 IST WBJEE: Gravitation

There are various Engineering Entrance Examinations in India like JEE (JEE Main & JEE Advanced), UPSEE, WBJEE and so on. JEE is a national level examination while USPEE and WBJEE are state level examinations. It is more difficult to crack JEE Examination than cracking state level examinations (i.e., USPEE and WBJEE). To help students to crack WBJEE Examination 2018 we bring chapter notes of chapter Gravitation including all important topics like law of orbits, law of periods, law of areas, gravitational force, acceleration due to gravity, gravitational potential energy, orbital velocity etc. This will help you to revise all important concepts instead of revising the complete chapter just before the examination.

West Bengal Joint Entrance Examination (WBJEE) is a state level common entrance test organized by West Bengal Joint Entrance Examinations Board for admission to the Undergraduate Level Engineering and Medical Courses through a common entrance test in the State of West Bengal.

Important Concepts:

Important Questions and Preparation Tips – Rotational Motion

Some previous years solved questions are given below:

Question 1:

A satellite has kinetic energy K, potential energy V and total energy E. Which of the following statements is true?

(A) K = –V/2

(B) K = V/2

(C) E = K/2

(D) E = –K/2

Solution 1:

Hence, the correct option is (A).

Important Questions and Preparation Tips – Centre of Mass

Question 2:

Two particles of mass m1 and m2 ,approach each other due to their mutual gravitational attraction only. Then

(A) accelerations of both the particles are equal

(B) acceleration of the particle of mass m1 is proportional to m1

(C) acceleration of the particle of mass m1 is proportional to m2

(D) acceleration of the particle of mass m1 is inversely proportional to m1

Solution 2:

Hence, the correct option is (C).

Important Questions and Preparation Tips – Laws of Motion

Question 3:

An artificial satellite moves in a circular orbit around the earth. Total energy of the satellite is given by E. The potential energy of the satellite is

(A) –2E

(B) 2E

(C) 2E/3

(D) –2E/3

Solution 3:

Let the potential energy of the satellite be PE and total energy be TE.

PE = 2(TE)

Given, TE = E

PE = 2E

Hence, the correct option is (B).

Question 4:

The escape speed of a body from the earth depend on

(A) the mass of the body,

(B) the location from where it is projected,

(C) the direction of projection,

(D) the height of the location from where the body is launched?

Solution 4:

(A) No

(B) No

(C) No

(D) Yes

Explanation: Escape Velocity of a body from the Earth is given by the relation:

g = Acceleration due to gravity

R = Radius of the Earth

It is clear from equation (i) that escape velocity Vesc is independent of the mass of the body and the direction of its protection. However, it depends on the gravitational potential at the point from where the body is launched. Since this potential marginally depends on the height of the point, escape velocity also marginally depends on these factors.

Hence, the correct option is (D).

Important Questions and Preparation Tips – Kinematics

Question 5:

Which of the following symptoms is not likely to afflict an astronaut in space?

(A) swollen feet

(B) swollen face

(D) orientation problem

Solution 5:

(A) Legs hold the entire mass of a body in standing position due to gravitational pull. In space, an astronaut feels weightlessness because of the absence of gravity. Therefore, swollen feet of an astronaut does not affect him/her in space.

(B) A swollen face is caused generally because of apparent weightlessness in space. Sense organs such as eyes, ears nose, and mouth constitute a person's face. This symptom can affect an affect an astronaut in space.

(C) Headaches are caused because of mental strain. It can affect the working of an astronaut in in space.

(D) Space has different orientations. Therefore, orientation problem can affect an astronaut in space.

Hence, the correct option is (A).

WBJEE 2014 Solved Physics Question Paper

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