Question

The gravitational force on the surface of the moon is only 1/6^th as strong as the gravitational force on the earth. What is the weight in newton’s of a 100 kg object on the moon and on the earth?
1. 550N
2. 750N
3. 800N
4. 980N

Answer 1

Correct Answer - Option 4 : 980N

The correct answer is 98N.

Given data:

• Acceleration due to earth’s gravity = g_e = 9.8 m/s²
• Object’s mass, m = 100 kg
• Acceleration due to moon gravity = g_m
• Weight on the earth= W_e
• Weight on the moon = W_m
• Weight = mass x gravity
• g_m = (1/6) g_e (given)
• So, W_m = m g_m
  • W_m= m x (1/6) g_e
• Weight on the moon
  • W_m = 100 x (1/6) x 9.8
  • W_m =163.4 N
• Weight on the earth-
  • W_e = m x g_e = 10 x 9.8
  • W_e = 980N

• The universal law of gravitation states that every object in the universe attracts every other object with a force called the gravitational force.
• The force acting between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres.
• For two objects of masses, m₁and m₂and the distance between them r, the force F of attraction acting between them is given by the universal law of gravitation 
• F α m₁m₂/r²
• Then the new Force is 
  F = G (m_1 x m₂)/r²
• Where G is the universal gravitation constant given by- G=6.67x10^-11Nm²Kg^-2

• Acceleration Due to Gravity: ( g = 9.81 m/s^-2)
  • The force of attraction exerted by the earth on a body is called gravitational pull or gravity.
  • We know that when a force acts on a body, it produces acceleration.
  • Therefore, a body under the effect of gravitational pull must accelerate.
  • The acceleration produced in the motion of a body under the effect of gravity is called acceleration due to gravity, it is denoted by g.
  • The acceleration due to gravity on the surface of the earth is given by,
  • g = GM/R²