** Speed:**** **the rate of motion, or the rate of change of position. It is expressed as distance moved (d) per unit of time(t). Speed is a scalar quantity with dimensions distance/time. Speed is measured in the same physical units of measurement as velocity.

Example: For human beings, an average walking speed is about 3 mph (~5 km/h, 1.39m/s),

The speed of long distance jogging for average persons is about 6 mph (~10 km/h, 2.7 m/s).Top athletic sprinters can run at 23.03 mph (~36.85 km/h, 10.24 m/s) within a short distance such as a 200 meters dash. Cycling can average 12 mph (~20 km/h, 5.56 m/s) Car can average 65 mph (~104 km/h, 28.9 m/s ) on highway