Mass & Weight

Weight = force of gravity = mass x free fall acceleration = ma = mg

Force = Weight = mg

 the acceleration of free fall for a body near to the Earth is constant


10 m/s2 = 10 N/kg

  •  Weight is the force which causes an object to accelerate downwards and has the value mg.
  • The value of the acceleration caused by weight can be calculated from Newton’s second law, using the equation F = ma
  • Weight unit is N (because it is a force)
  • It is measured by spring balance


 Mass   Weight
Define It is the amount that body contains“It is not a force” It is the force of gravity acting on the body“It is a force”
Units kg (kg.m/s2)
Scalar or vector Scalar quantity(No direction) Vector quantity(always vertical downwards)
Device used to measure Pan balance.Beam balance. Spring balance
Dependence on place Mass of a body remains the same throughout the universe
(doesn’t change from one place to another)
Weight varies from one place to another depends on the value of (g) which is the acceleration due to gravity.
The relationship between them Weight = mg


  1. The weight of any object on the moon is 1/6 its weight on the earth, so gmoon = 1.67 m/s2.
  2. If the weight of 1kg mass will be 10 N, and since the weight = 10 x mass, so if you measure your weight on a scale (on earth) and your weight was 600 N, we can write it on the scale as 60 kg.
  3. The acceleration due to gravity is constant at the same place and height, can be taken as …… 10 m/s2.
  4. Free fall acceleration = g = weight / mass = constant (10 m/s2).

Gravitational force


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