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
|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”|
|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
- The weight of any object on the moon is 1/6 its weight on the earth, so gmoon = 1.67 m/s2.
- 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.
- The acceleration due to gravity is constant at the same place and height, can be taken as …… 10 m/s2.
- Free fall acceleration = g = weight / mass = constant (10 m/s2).