The Pull of the Earth – Maharashtra Board Class 9 Solutions for Science and Technology (English Medium)
AlgebraGeometryScience and TechnologyHindi
Solution 1:
 The ratio g (earth) /g (moon) is equal to 6:1.
 The value of the acceleration due to gravity increases as we move from the equator to the pole.
 If the earth shrinks to half of its radius, its mass remaining the same, the weight of an object on the earth will become four times
Solution 2:
Solution 3:
Solution 4:
The following factors affect the value of g:

 Shape of the Earth: The Earth is not perfectly spherical in shape. It is slightly flattened at the poles and bulges towards the equator. The value of g is maximum (9.83 m/s^{2}) at the poles as the polar radius is minimum, while it is minimum (9.78 m/s^{2}) at the equator as the equatorial radius is maximum.
 Depth: In the interior of the Earth, on an average, the value of g is less than that at the Earth’s surface. As the depth below the Earth’s surface increases, the value of g decreases, and finally, it becomes zero at the centre of the Earth.
Solution 5.1:
Mass  Weight  
1  The mass of a body is the quantity of matter contained in it.  The weight of a body is the gravitational force with which the Earth attracts it towards its centre. 
2  It has magnitude but not direction.  It has both magnitude and direction. 
3  It does not change from place to place.  It changes from place to place. 
4  It can never be zero.  It is zero at the centre of the Earth. 
5  The SI unit of mass is kilogram.  The SI unit of weight is newton. 
Solution 5.2:
Universal gravitational constant  Gravitational acceleration of Earth  
1  Universal gravitational constant numerically equals to the force of attraction between two unit masses separated by a unit distance.  Gravitational acceleration of the Earth is the acceleration produced in a body due to the gravitational force of the Earth. 
2  Its value remains constant throughout the Universe.  Its value changes from place to place. 
3  It has magnitude but not direction.  It has both magnitude and direction. 
4  Its SI unit is Nm^{2}/kg^{2}.  Its SI unit is m/s^{2}. 
Solution 6:
 The weight of a body is given by W = mg, where m is the mass of the body and g is the acceleration due to gravity. The value of g at the equator is less than that at poles. So, the value of g varies from place to place and m is the same everywhere.
 Hence, the weight of silver bought at the North Pole would be less when weighed at the equator. Therefore, Rahul’s friend will disagree about the weight of the silver.
Solution 7.1:
Data: W = 100N, g = 1.63 m/s^{2}, m = ?
W = mg
The mass of the body is 61.35 kg.
Solution 7.2:
Data: g = 9.8 m/s^{2},
M_{p} = 2M_{e}, R_{p} =2R_{e}, g_{p} = ?
Acceleration due to gravity,