# Motion and Speed

### Motion:

Motion is considered by many as one of the interesting topics in physics. Generally, an object is said to be in motion whenever it moves. In fact, we live in a universe where everything moves, although at a different rate. For instance:

• The earth orbits or revolves round the sun.
• The moon revolves round the earth (as earth’s satellite).

In physics, motion is defined as a change in the position of an object with reference to time.

Although we sometimes sit or stand in a fixed position, that doesn’t mean motion isn’t taking place. The fact that the earth is rotating implies that we are indirectly moving along with it. We can thus say that motion can be relative to some frame of reference.

In the above paragraph, the earth (constantly rotating along its axis) is our frame of reference and everything present on earth is in motion (with regard to earth as a frame of reference).

In another instance, a person statically seated in a moving bus also undergoes motion. Although such person appears to be static (not moving); but since the bus is in motion (moving), we can correctly conclude that the motion of the person sitting inside the bus is relative to the bus.

Force is responsible for the motion or movements present in the universe.

For an object to move, a force must act upon it. Consider the instance below:

If we keep a pin in a vacuum and it’s left untouched, the pin will remain in that position unless it is acted upon by a force. This force could be in the form of an applied air or a deliberate touch.

In order to get a better understanding of motion, it is important we know how the following terms work since they all involved in motion. The terms are:

1. Speed
2. Velocity
3. Acceleration

### Speed

Speed is simply the rate of motion since it is a measure of how fast or slow an object is moving.

The dimensions associated with speed are distance and time.

If one covers a distance of 10,000 meters in 50 seconds and another covers the same distance in 5,000 seconds, we can conclude that the first person has a greater speed because he covered the same distance at a lesser time.

Speed is defined as distance travelled per unit of time.

Speed can also be defined as the rate of change of distance.

Speed = distance/Time

Speed is a scalar quantity since it is has only magnitude. (Speed does not have a direction).

Time is a duration or period during which things happen. It is measured in seconds(s).

Distance is the total length of path traveled from one point to another. It is measured in meters (m).

Alfred Ajibola is a Medical Biochemist, a passionate Academician with over 7 years of experience, a Versatile Writer, a Web Developer, a Cisco Certified Network Associate and a Cisco CyberOps Associate.

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