Gravitation Test

Result

Gravitation Test - 8

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
1 / -0

If the earth is replaced by a small point sized particle of the same mass, it is the geodesic centre. How will the force of gravity change at the present surface of the earth? (Assuming the earth to be a perfect sphere)

A
Increases

B
Decreases

C
Varies from place to place

D
No change

Solution

While calculating the gravity at any point, the distance of point is considered from the centre of the earth. Hence, even if the earth is replaced by a small point sized particle of the same mass, the distance of a point at the present surface of the earth remains the same. Therefore, the gravity will remain the same.
Question 2
1 / -0

What causes tides?
(i) Attraction of sun
(ii) Attraction of moon
(iii) Attraction of earth

A
(i) and (iii)

B
(ii) and (iii)

C
(i) and (ii)

D
Only (i)

Solution

Gravitation attraction of the sun and the moon on the oceans of the earth are responsible for tides.
Thus, option (3) is correct.
Question 3
1 / -0

If somehow, the distance between the Sun and Earth is doubled, then the gravitational force between them will become

A
double

B
half

C
four times

D
one-fourth

Solution

F = Gm₁m₂/r²,where F = gravitation force between the Sun and Earth, G = universal gravitation constant, m₁ = mass of the Sun, m₂ = mass of Earth and r = distance between the Sun and Earth.
Now, when the distance between the two bodies is doubled, the distance becomes 2r and the force is denoted by F'.
F' = Gm₁m₂/(2r)²F' = F/4
Thus, option 4 is correct.
Question 4
1 / -0

At what height above the Earth's surface is the acceleration due to gravity 1% less than its value at the surface?

A
16 km

B
32 km

C
64 km

D
32km

Solution
Question 5
1 / -0

A planet has twice the values of mass and radius as of Earth. Acceleration due to gravity on the surface of this planet is

A
9.8 m/s²

B
4.9 m/s²

C
980 m/s²

D
19.6 m/s²

Solution

g = GM/R²g' = G(2M)/(2R)²g' = g/2 = (9.8/2) m/s² = 4.9 m/s²
Question 6
1 / -0

Two planets have radii r₁ and r₂ and densities d₁ and d₂. The ratio of acceleration due to gravity on them will be

A
r₁d₂ : r₂d₁

B
r₁d₁ : r₂d₂

C

D

Solution

g = GM/
g₁ = G x d₁x (4/3 )/
g₁ = Gd₁ x (4/3)
Similarly,
g₂ = Gd₂ x (4/3)
g₁/g₂ = r₁d₁/r₂d₂
Question 7
1 / -0

The rate of fall of g on going up the earth's surface is ______ the rate when going down the earth's surface.

A
double

B
half

C
quarter

D
quadruple

Solution

Moreover at the center of the earth, the force of gravity is maximum. So, the rate of fall of gravity going up the earth's surface is double the rate when going down the earth's surface.
Question 8
1 / -0

The weights of an object in a coal mine, at sea level and on the top of a mountain are W₁, W₂and W₃,respectively. Which of the following relations holds true?

A
W₁ < W₂ > W₃

B
W₁ = W₂ = W₃

C
W₁ > W₂ > W₃

D
W₁ < W₂ < W₃

Solution

W₁ < W₂ > W₃is correct.
The weight of an object in a coal mine is lesser than the weight of that object at sea level. The weight of an object is lesser on the top of a mountain than at sea level.
Question 9
1 / -0

An object shoots off perpendicularly from the earth with a velocity 4/5 times the escape velocity. What will be the maximum height from the surface of the earth up to which the object will rise? (Given: R = radius of earth)

A
(25/9)R

B
(25/41)R

C
(16/9)R

D
(25/16)R

Solution
Question 10
1 / -0

Which of the following statements are true?
(i) Orbital velocity is more than escape velocity.
(ii) Escape velocity is times the orbital velocity.
(iii) Orbital velocity increases with radius.
(iv) A body with a velocity equal to the orbital velocity will orbit the planet in a circular path.

A
(i) and (ii)

B
(ii) and (iv)

C
(iii) and (ii)

D
(iii) and (iv)

Solution

(i) Escape velocity is times the orbital velocity.
(ii) A body with a velocity equal to the orbital velocity will orbit the planet in a circular path.
Question 11
1 / -0

Escape velocity of a projectile from the surface of earth is about

A
3 10¹⁰ cm/s

B
18600 m/s

C
11.2 km/s

D
8 km/s

Solution

Escape velocity of a projectile from the surface of earth is about 11.2 km/s
Question 12
1 / -0

A pendulum has a velocity v at the lowest point. What is the maximum height reached by it?

A
v²/g

B
2v²/g

C
v²/2g

D
v²/4g

Solution

Let d be the maximum height reaches by the pendulum
v² = 2gd
d = v²/2g
Question 13
1 / -0

An object is orbiting at double its original radius. Its orbital velocity has changed by a factor of

A
1/

B

C

D
2

Solution

v =
v' =
Question 14
1 / -0

The mass of a satellite increases by a factor of two. The orbital velocity

A
becomes twice

B
becomes thrice

C
remains unchanged

D
insufficient information

Solution

The mass of a satellite increases by a factor of two. The orbital velocity remains unchanged because orbital velocity of satellite does not depend upon the mass of the satellite.
Question 15
1 / -0

Inside a satellite, orbiting very close the earth's surface, water does not fall out of a glass when it is inverted. Which of the following is the best explanation for this?

A
The earth does not exert any force on the water.

B
The earth's force of attraction on the water is exactly balanced by the force created by the satellite's motion.

C
The water and the glass have the same acceleration, equal to g, towards the centre of the earth. Hence, there is no relative motion between them.

D
The gravitational attraction between the glass and the water balances the earth's attraction on the water.

Solution

The water and the glass have the same acceleration, equal to g, towards the centre of the earth. Hence, there is no relative motion between them.
Question 16
1 / -0

Which of the following is not a statement of Kepler's Law?

A
Line joining planet and sun sweeps equal areas in equal time.

B
Square of time period is proportional to cube of radius.

C
Planets move around the sun in a circular orbit.

D
Planets move around the sun in an elliptical orbit with sun at one of the foci.

Solution

Planets move around the sun in a circular orbit is not a statement of Kepler's Law.
Question 17
1 / -0

A planet goes around the sun twice as many times as earth in a given time interval.

A
It has a higher radius of orbit.

B
It has a lower radius of orbit.

C
It covers equal area to earth in equal time.

D
It has slower velocity than earth.

Solution

As Kepler's third law states that square of the time period is directly proportional to the cube of the semi major axis .

hence lesser is the time period of revolution lesser is the radius of the orbit.
Question 18
1 / -0

A satellite going round the earth in a circular orbit loses some energy due to a collision. If its speed is v and distance from the earth is d, which of the following is correct?

A
If d increases, v will increase.

B
If d increases, v will decrease.

C
If d decreases, v will decrease.

D
If d decreases, v will increase.

Solution
Question 19
1 / -0

When a planet moves around the sun, its

A
areal velocity is constant

B
linear velocity is constant

C
angular velocity is constant

D
all the velocities are constant

Solution

When a planet moves around the sun, its areal velocity is constant
Question 20
1 / -0

When a body moves with high speed, albeit, much below the speed of light, its mass

A
remains unchanged

B
decreases

C
increases

D
none of the above

Solution

In Newtonian physics, the masss of a body is not dependent on the speed of the body.
Thus, option (1) is correct.