The weight of an object and its mass are directly proportional. For a given gravitational field strength, the greater the mass of the object - the greater its weight is.
Weight can be calculated using the equation:
weight = mass × gravitational field strength
This is when:
An apple has a mass of 100 g. Calculate its weight on Earth (g = 10 N/kg).
100 g = 100 ÷ 1000 = 0.1 kg
Calculate the weight of a 30 kg dog (g = 10 N/kg).
To make a measurement of weight, we have to measure the force pulling the object towards the centre of the Earth. We do this by balancing it with a known force. If the object is stationary, Newton's third law then tells us that the known force is the same as the weight.
A spring balance will stretch until the force from the spring is enough to balance the weight of the object, and the distance the spring in it has stretched indicates the force it is exerting to hold up the object.