Gravity is an invisible force that attracts objects towards each other. This becomes very noticeable when dealing with large bodies of mass, such as planets. This is because the greater the object’s mass is, the greater the gravitational force. Gravitational forces pulls inwards, towards the object’s centre. This is why on Earth, we are pulled towards the ground.
All objects have mass, which can only change when you add more mass or remove mass. However, weight does change, as it is a force that depends on gravity. As seen in the example below on the left, when on Earth, the elevator falls due to gravity. This is because it is on Earth, within the Earth’s gravitational pull. In space, the man becomes weightless and therefore floats because he is outside of Earth’s gravitational pull. So, he is no longer drawn towards Earth’s centre.
When an object falls towards Earth, it gets faster due to the force of gravity. The rate at which an object falls to the ground depends on how much air resistance there is.
The opposing force in this case is air resistance, an upward force of friction, with the purpose to slow the object down. Air resistance opposes gravity. There is an increase in air resistance when you increase the surface area of the object.
However, objects fall differently depending on how gravity and air resistance interact. For example, if you dropped an apple and a feather at the same time:
Feathers float and take their time to reach the ground, whereas an apple just falls straight to the ground. This is because there is much greater air resistance when the feather is falling compared to the apple.
The apple can fall through the air at a faster rate. This is due to Galileo’s discovery, that objects which are more dense (or have more mass) will fall at a faster rate than objects which are less dense (or have less mass), as a result of air resistance.
When a feather and an apple are dropped at the same time, air resistance causes the feather to drop slower than the apple. However, in a vacuum (such as space), where there is no air resistance, the apple and the feather would fall at the same rate and reach the ground at the same time.