1. Home
  2. Worksheet For class 9
  3. Maharashtra board Worksheet for class 9 science Physics
  4. SSC Worksheet for chapter-4 Pull of The Earth class 9

SSC Worksheet for chapter-4 Pull of The Earth class 9

Worksheet For class 9

Fill in the Blanks

  1. A body on earth will have weight approximately ________times its weight on the moon.
  2. The SI unit of universal gravitational constant G is _______ .
  3. The value of acceleration due to gravity g at the centre of earth is _______ .
  4. The value of acceleration due to gravity on the earth is maximum at the _______.
  5. If radius of earth doubles, with its mass remaining same, the weight of an object on earth will become________ times its original weight.
  6. The SI unit of weight is ______
  7. From Newton’s first law of motion, we infer that_________ is a measure of inertia of any object
  8. State Newton’s Law of gravitation and express it in mathematical form.
  9. Write a note on ‘gravity’
  10. Explain the factors affecting the value of acceleration due to gravity ‘g’.
  11. Differentiate between
  • Mass and weight
  • Universal gravitational content and gravitational acceleration of earth
  1. From Newton’s law of gravitation, derive formula for acceleration due to gravity on a given planet.
  2. Why is weight of the same body different on planets?
  3. Find the gravitational force of attraction between two bodies of masses 10 kg and 40 kg, their centers being separated by a distance of 200 m. Take G = 6.67 x 10–11 Nm2/ Kg2
  4. If acceleration due to gravity on surface of earth is 9.8 m/s2, find acceleration due to gravity on surface of a planet whose mass is three times that of earth and diameter is twice that of earth
  5. A particle is released from top of a building of height 19.6 m. Find velocity with which particle hits the ground. (Take g = 9.8 m/s2)
  6. A stone dropped from top of a tower takes 3 seconds to strike the ground. Find height of tower. (Take g= 9.8 m/s2)

Solutions

  1. Six
  2. Nm2/ Kg2
  3. 0 4. Poles
  4. pole
  5. 1/4
  6. Newton
  7. Mass
  8. Every point massattracts every single other point mass by a forcepointing along the lineintersecting both points. The force isproportionalto the productof the twomassesandinversely proportionalto thesquareof the distance between them.

Vector form

F12=-G (m1 m2)/|r12 | r 12

where F12is the force applied on object 2 due to object 1,

Gis the gravitational constant,

m1andm2are respectively the masses of objects 1 and 2,

|r12| = |r2−r1| is the distance between objects 1 and 2, and

r 12≝(r2-r1)/|r2-r1 | is the unit vectorfrom object 1 to 2.

  1. Gravitation is a natural phenomenon by which objects with mass attract one another. In everyday life, gravitation is most commonly thought of as the agency which lends weight to objects with mass. Gravitation compels dispersed matter to coalesce, thus it accounts for the very existence of the Earth, the Sun, and most of the macroscopic objects in the universe. It is responsible for keeping the Earth and the other planets in their orbits around the Sun; for keeping the Moon in its orbit around the Earth, for the formation of tides; for convection by which fluid flow occurs under the influence of a temperature gradient and gravity); for heating the interiors of forming stars and planets to very high temperatures; and for various other phenomena that we observe. Modern physics describes gravitation using the general theory of relativity, in which gravitation is a consequence of the curvature of space time which governs the motion of inertial objects.
  2. Factors affecting value of acceleration due to gravity
  • Altitude: With increase in height g decreases.
  • Depth: With increase in depth below the surface, g decreases.
  • Due to rotation of Earth, ‘g’ is maximum at the poles and minimum at the equator.

11.

(i)

Mass Weight
Is always a constant any place and time Depends on gravity at the place
Is measured in kilograms in SI unit Is measured in Newton (not in kilograms as one might think)
Is measured using balance Is measured using scales
Can never be zero Can also zero
Is an intrinsic property and is independent of any external factor.

Depends on

1. Mass of the object which is attracting it

2. Force with which it is being attracted (which in turn depends on the distance between the two)

(ii)

Universal Gravitational constant (G) Gravitational acceleration(g)
G is called the Newtonian Gravitational Constant. It is fixed for any point in the universe Its value is very small (G=6.67 x10-11 m2/kg2) g represents the acceleration of an object due to the earth's gravity. g=9.8 m/s2 g varies for different heights. For example, if you go to a mountain on Earth, value of g will slightly change.

12. F = GMm/r2 … (i) (Newton law of gravitation)

F = ma … (ii) (Newton 2nd law)

From (i) and (ii)

GMm/r2 = ma

d = GM /r2

13. Weight depends on acceleration due to gravity this gravity will be different on different planets because the planets themselves have different masses that is gravity is a result of mass, the stronger the gravitational pull.

14. F = Gm1m2/r2

= 6.67 x 10-11 x 10 x 40/(200)2

= 2.64 x 10-8 / 40000

= 6.6 x 10-13 newtons

15. ge = 9.8m/s2

Mearth = M, dearth = d, rearth = d/2

Mplanet = 3M, dplanet = 2d, rplanet = (2d/2)

g = GM/r2

=ge/gp = GMe/re2 / GMp/r2p

ge/gp = M/3M(d/ d/2)2

ge/gp = 22/3 = 4/3

gp = ge x 3/4

gp = 9.8 x 3/4 = 7.35m/s2

16. h = 19.6m, u = 0

v2-u2 = 2as

v2-(0)2 = 2 x 9.8 x (19.6)

v = √2 x 9.8 x (19.6)

v = 19.6m/s

17. u = 0 , t= 3sec, h=?

S = ut + 1/2 at2

S = 0+ 1/2 x 9.8 x 32

S = 44.1 meters

Also Check

Related Link

Talk to Our counsellor