The of a position-time graph represents an object’s velocity.

The slope of a position-time graph represents an object’s velocity.

Explanation:

In a position-time graph, the values on the x-axis represent the time, while the values on the y-axis represent the position of the object.

Velocity is defined as the ratio between the displacement of an object and the time taken:

However, we can see that this definition corresponds to the slope of the curve in a position-time graph. In fact:

, the displacement, corresponds to the difference in position, so the difference between the values on the y-axis:

, the time interval, corresponds to the difference in times, so the difference between the values on the x-axis:

So, the velocity is

which corresponds to the slope of the curve.

the closer the planet is to the sun, the larger the gravity