Understanding Free-Fall (acceleration due to gravity)

On earth, the gravitational field strength is 10 N/kg and the acceleration due to gravity is 10 ms-2.

That means when you release an object from you hand, the object will fall with increasing speed. The acceleration is a constant 10 ms-2 (acceleration due to gravity). Simply put, it means in 1 second, the speed of the object will increase by 10 m/s.

In general, if there is no air resistance or air resistance is negligible, the speed-time graph is a straight line with constant gradient and passes through origin, i.e. speed is directly proportional to the time.

If there is air resistance, there is a maximum constant speed if the object continues to fall. Hence the graph is different.

More importantly, remember that any object that you released on earth, whether there is air resistance or no air resistance, the initial acceleration when it is released is always a constant 10 ms-2!

Refer to the video for the explanation and some examples.