gravitation jee mains questions with solutions

gravitation jee mains questions with solutions

Welcome, To STUDYEVERTHING
Today, we are going to cover the MOST IMPORTANT QUESTION from PHYSICS chapter Gravitation for exams like CBSE board, NEET, JEE MAIN & JEE ADVANCE.

First try to solve the question on your own in the allotted time as shown in table. Then check the answers.

If you want to know the answers in detail you can simply download the pdf file which is at the end of the session.

So, what are you waiting for,
Let's crack it.

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STUDY EVERTHING

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Section	no of questions	Alloted Time	Type	Question level
Type 1	10	45 min	Mcq	Moderate
Type 2	5	--	Integer	Moderate
Type 3	5	--	Mcq	Tough

Quick Recap

Newton law of Gravitation 

 F=Gm₁m₂/r²

Universal Gravitational constant 

G=6.67×10^-11Nm²/kg^2.

Change in value of g 

1. Minimum at equator.
2. Maximum at poles.
3. Value of g at height h above earth surface is g'= g(1-2h/R)
4. Value of g at depth h below earth's surface is g'= g(1-h/R).
Here, R represent radius of earth.

Gravitational Field 

E=GM/r².
It's SI unit is Nk/g.

Gravitational potential 

 V=-GM/r
It's SI unit is J/kg.

Gravatational potential energy 

 U=-Gm₁m₂/r

Kepler's law of planetary motion 

1st law: Every planet revolve round the sun in an elliptical orbit with the sun at one focus of the ellipse.
2nd law: The line joining the sun to the planet sweeps out equal area in equal interval of time.
3rd law: The square of time period of revolution is directly proportional to the cube of average distance of the planet round the sun. 

Orbital velocity of satellite 

 v=R(g/R+h)^1/2

Time period of satellite 

 T=2π(R/g)^1/2

Energy of satellite 

Gravatational potential energy
U=-GMm/r
Kinetic energy =1/2GMm/r
Binding energy of satellite E=1/2GMm/r

Escape velocity 

v=(2GM/R)^1/2=(2gR)^1/2
It's value for earth's surface is 11.2km/s

Esacape Energy 

U=GMm/R




Let's begin

TIMER:

45min

Type 1 MCQ

1.If the radius of the earth were to shrink by one percent, its mass remaining the same, the acceleration due to gravity on the earth's surface would 

a.decrease
b.remain unchanged
c.increase
d.be zero

2. The weight of body will increase significantly if it is taken.

a. to the centre of the earth
b. to the top of mountain
c.from the pole to the equator
d.from the equator to the pole.

 3. A satellite is moving with a constant speed 'V' in a circular orbit about the earth. An object of mass 'm' is ejected from the satellite such that it just escape the gravitational pull of the earth. At the time of ejection kinetic energy of the object is 

a.1/2MV²
b.mV²
c.3/2mV²
d.2mV²

4. The apparent weight of the body on the surface of the earth at latitude λ will be 

a.mg/sinλ
b.mgsinλ
c.mg/cosλ
d mgcosλ

5. The time period of the earth is 5 hour. The separation between the earth and satellite is increased the 4 times the pervious value. The new time period will be

a.10 hours
b.80 hours
c.40 hours
d 20 hours

6. The escape velocity for a body projected vertically upward from the surface of the earth is 11 km/sec. If the body is projected at an angle 45° with the vertical, the escape velocity will be 

a.11√2 km/sec
b.22 km/sec
c.11 km/sec
d 11/√2 km/sec

7. Two spherical bodies of mass M and 5M and radii R and 2R are released in free space with initial separation between their centres equal to 12R. If they attract each other due to gravitational force only, then the distance covered by smaller body just before the collision is

a.2.5R
b.4.5R
c.7.5R
d 1.5R

8. A particle of mass 10g is kept on the surface of uniform sphere of mass 1000kg and of uniform radius 10cm. Find the work to be done against the gravitational force between them to take the particle far away from the sphere (G= 6.67×10^-11Nm² 2/kg²)

a.3.33×10^-10J
b.13.34×10^-10J
c.6.67×10^-10
d 6.67×10^-9J

9. Average density of the earth 

a.is complex function of g
b.is does not depend on g
c.is inversely proportional to g
d is directly proportional to g

10. A satellite is revolving in a circular orbit at a height 'he's from the earth's surface ( radius of earth R; h<<R). The minimum increase in orbital velocity required, so that satellite could not escape the earth's gravitational field, is close to (Neglect the effect of atmosphere ).

a.√gR/2
b.√gR(√2-1)
c.√2gR
d √gR

Type 2        NUMERICAL TYPE

1. If the earth moves round the sun in a circular orbit of radius 150.000.000km with an angular velocity of about 0.01745 rad/day. Its linear speedin km/s is approximately 

2. The escape velocity of a body on the surface of the earth is 11.2km/s. What is the escape velocity of the body on the surface of a planet which is 32times as heavy as the earth and whose radius is twice the radius of the earth?( in km/s)

3. The ratio of the radius of earth to that of of moon is 10. The ratio  of acceleration due to gravity on the earth and on the moon is 6. The ratio of the escape velocity from the earth's surface to that from the moon is

4. If the distance between sun and the earth were half its present value, the number of days a year would have been 

5. Time period of the satellite of the earth is 5 hour if the separation between the earth and the satellite is increased to 4 times the pervious value the new time period will be (in hours)

Type 3    JEE ADVANCE 

1. A planet of radius R=1/10(the radius of the earth) has same mass density as Earth. Scientists dig a well of depth R/5 on it and lower the wire of same length and linear mass density 10¹-3 kg/m into it, if the wire is not touching anywhere the force applied at the top of the wire by a person holding it in a place is

Given Radius of earth R=6.6×10⁶m and acceleration due to gravity on earth g=10m/s²

a.96N
b.108N
c.120N
d.150N

2. Gravitational acceleration on the surface of the planet is √11/6 g where g is gravitational acceleration on the surface of the earth. The average density of the planet is 2/3 times that of the earth. If escape speed on the surface of the earth is 11m/s. The escape speed on the surface of planet is

a.3
b.8
c.10
d.2

3. A bullet is fired vertical upward with a velocity v from the surface of a spherical planet, when it reaches its maximum height  its acceleration due to planets gravity is 1/4 of its value of the surface of the planet. The escape velocity from the surface of the planet is v=v√N times. The value of the N is  

a.3
b.2
c.6
d.9

4. A large spherical mass M is fixed at one position and two identical point mass m are kept on the line passing through the centre of M (see figure). The point mass are connected by rigid massless rod of length l and this assembly is free to move along the line connecting them. All three masses interact only through their mutual gravitational interaction. When the point mass nearer to M at a distance r=3l, from M tension in the rod is zero m= k(M/288). The value of k is 

a.15
b.20
c.7
d.3

5. Two satellite S₁1 and S₁ revolve around a planet in coplaner circular orbit into he same sense. Their period of revolution is 1 hour and 8 hours respectively. The radius of the orbit S₁ is 10⁴km. When S₂ is closest to S₁, find the speed of S₂ relative to S ₁.

a.1
b.5
c.7
d.9

Download the detailed answer pdf of the most important questions from Chapter
Gravitation.

Unit and measurements  most important  questions	click here
Kinamatic most important questions	click here
Law of motion most important questions	click here
Work, energy and power most important questions	click here
Nit cutoff	click here
Iiit cutoff	click here

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black holes facts

Blackhole is a massive interstitial body having a very strong gravitational force of attraction such that even light can't escape.

It destroyed space and time hence our physics laws can't be applied thereafter the event horizon.

The event horizon is a place where the black hole started.

Study reveals that we see aren't seeing it from the front. The visible portion to us is its back-side.

A study found that if a person falls in the black hole then his body parts start stretching and keep stretching until infinity.

Black holes may be the way to interact with higher dimensional power which is known as Gods.

Sagittarius A*, at the center of the Milky Way, is the closest supermassive black hole, some 25,000 light-years distant from our solar system.

Black holes are one of the biggest mystery in our universe which is not unrevealed yet.

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