(a) Define speed. What is the SI unit of speed?
(b) What is meant by (i) average speed, and (ii) uniform speed?
(a) Speed is the distance traveled per unit of time. It is how fast an object is moving. Speed and velocity are both measured using the same units. The SI unit of distance and displacement is the metre. The SI unit of time is the second. The SI unit of speed and velocity is the ratio of two- metre per second (m/s).
(b) Average Speed: The average speed of a body is the total distance traveled divided by the total time taken to cover this distance.
Average Speed = Total distance travelledTotal time taken
eg. For a car which travels a distance of 100 km in 4 hours , the average speed is 1004=25kmhr
Uniform Speed: A body has a uniform speed if it travels equal distances in equal intervals of time.
Eg. A car is said to have a uniform speed of 20kmhr, if it travels 10 km every half hour.