Dashboard
Physics
Gravitation
NCERT Solutions
NCERT Solutions
Gravitation
7 Solutions
Q1
EXERCISES
Answer the following :
(a)
You can shield a charge from electrical forces by putting it inside a hollow conductor. Can you shield a body from the gravitational influence of nearby matter by putting it inside a hollow sphere or by some other means ?
(b)
An astronaut inside a small space ship orbiting around the earth cannot detect gravity. If the space station orbiting around the earth has a large size, can he hope to detect gravity?
(c)
If you compare the gravitational force on the earth due to the sun to that due to the moon, you would find that the Sun's pull is greater than the moon's pull. (you can check this yourself using the data available in the succeeding exercises). However, the tidal effect of the moon's pull is greater than the tidal effect of sun. Why?
Q2
EXERCISES
Choose the correct alternative :
(a)
Acceleration due to gravity increases/decreases with increasing altitude.
(b)
Acceleration due to gravity increases/decreases with increasing depth (assume the earth to be a sphere of uniform density).
(c)
Acceleration due to gravity is independent of mass of the earth/mass of the body.
(d)
The formula
−
G
M
m
(
1
/
r
2
−
1
/
r
1
)
-G M m(1 / r_{2}-1 / r_{1})
−
GM
m
(
1/
r
2
−
1/
r
1
)
is more/less accurate than the formula
m
g
(
r
2
−
r
1
)
m g(r_{2}-r_{1})
m
g
(
r
2
−
r
1
)
for the difference of potential energy between two points
r
2
r_{2}
r
2
and
r
1
r_{1}
r
1
distance away from the centre of the earth.
Q3
EXERCISES
Suppose there existed a planet that went around the Sun twice as fast as the earth. What would be its orbital size as compared to that of the earth ?
Q4
EXERCISES
Io, one of the satellites of Jupiter, has an orbital period of 1.769 days and the radius of the orbit is
4.22
×
10
8
m
4.22 \times 10^{8} \text{ m}
4.22
×
1
0
8
m
. Show that the mass of Jupiter is about one-thousandth that of the sun.
Q5
EXERCISES
Let us assume that our galaxy consists of
2.5
×
10
11
2.5 \times 10^{11}
2.5
×
1
0
11
stars each of one solar mass. How long will a star at a distance of 50,000 ly from the galactic centre take to complete one revolution? Take the diameter of the Milky Way to be
10
5
ly
10^{5} \text{ ly}
1
0
5
ly
.
Q6
EXERCISES
Choose the correct alternative:
(a)
If the zero of potential energy is at infinity, the total energy of an orbiting satellite is negative of its kinetic/potential energy.
(b)
The energy required to launch an orbiting satellite out of earth's gravitational influence is more/less than the energy required to project a stationary object at the same height (as the satellite) out of earth's influence.
Q7
EXERCISES
Does 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?
Gravitation NCERT Solutions - Class 11 - Science Physics | Kedovo | Kedovo