Patterns of movement

The train in the photograph is moving. You can tell because it looks blurred. The grass is not blurred because it is stationary.

The train looks blurred because it takes the camera a friction of a second to take the picture. During this time, the train moves.

There are four types of speeds shown below:

Uniform Speed

In mathematics and physics, if an object is travelling in such a way that it covers the same distance for each interval of time it is travelling, then it is said to be travelling with uniform speed.

Variable Speed

An object is said to be in variable speed when the object covers a different distance in equal intervals at times.

Average Speed

Average speed is defined as the uniform speed which is given by the ratio of the total distance travelled by an object to the total time taken by the object.

Instantaneous Speed

When an object is moving with variable speed, then the speed of that object at any instant of time is known as instantaneous speed.

Constant speed, changing speed

The photograph below shows an owl flying. There is only one owl, not five. The camera has taken five pictures, one after the other. They were taken at equal interval of time.

From the photograph, you can tell that the owl is flying from left to right. You can also tell that it is flying at a constant speed, because the pictures are equally spaced.

The photograph below shows a steel ball bearing rolling down the slope. This shows that the ball bearing is speeding up.

So equal spacings tell us that an object is moving at a steady speed. Increasing spacings tell us that it is speeding up.