Distinguish between speed and velocity .Abdul ,while driving to school ,computes the average speed for his trip to be 20km/h.On hos return along the same route ,there is less traffic and the average speed is 30km/h.what is the average speed and average velocity for Abdul's trip.
Answers
The reason is simple. Speed is the time rate at which an object is moving along a path, while velocity is the rate and direction of an object's movement.
Case I: While driving to school
Average speed of Abdul’s trip = 20 km/h
Total distance = d
Let total time taken = t 1
Speed = Distance / time
20 = d / t 1
t 1 = d / 20…(i)
Case II: While returning from school
Total distance = d
Speed = 30 km/h
Now, total time taken = t 2
Speed = distance / time
30 = d / t 2
t 2 = d / 30 (ii)
Total distance covered in the trip = d + d = 2d
Total time taken, t = Time taken to go to school + Time taken to return to school
= t 1 + T 2
Total time taken = d / 20 + d / 30
= 3d + 2d / 60
= 5d / 60
= d / 12
From equations (i) and (ii),
Average Speed = 120/5
= 24 km/h
Hence, the average speed for abdul trip is 24 km/h.