4.5.1.3 Gravity

# 4.5.1.3 Gravity

## Content

1. Weight is the force acting on an object due to gravity. The force of gravity close to the Earth is due to the gravitational field around the Earth.
2. The weight of an object depends on the gravitational field strength at the point where the object is

The weight of an object can be calculated using the equation:

weight = mass × gravitational field strengthW =mg

weight, W, in newtons, N mass, m, in kilograms, kg

gravitational field strength, g, in newtons per kilogram, N/kg (In any calculation the value of the gravitational field strength (g) will be given.)

The weight of an object may be considered to act at a single point referred to as the object’s ‘centre of mass’.

The weight of an object and the mass of an object are directly proportional.

Weight is measured using a calibrated spring-balance (a newtonmeter).

MS 3a-Understand the symbols: = < << >> >~

MS 3b Change the subject of an equation

MS 3c Substitute numerical values into algebraic equations using appropriate units for physical quantities

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