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.

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