Question

A car runs at a constant speed on a circular track of radius 150 m taking 62.8 s on each lap. The average speed and average velocity on each complete lap is (π = 3.14)

just asking for confirmation

Answer 1

Answer :-

→ Average speed of the car = 15 m/s

→ Average velocity of the car = 0 m/s

Explanation :-

For average speed :-

Distance travelled in each lap is equal to the circumference of the circle.

So, average speed of the car on each complete lap will be given by :-

v = Circumference/Time

⇒ v = 2πr/t

⇒ v = (2 × 3.14 × 150)/62.8

⇒ v = 942/62.8

⇒ v = 15 m/s

For average velocity :-

After completing each lap, the car will ultimately return at the same position from which it started. So initial and final points of the car are same .

∴ Displacement of the car = 0

Now, it's average velocity will be given by :-

v = Total displacement/Time

⇒ v = 0/62.8

⇒ v = 0 m/s

Answer 2

Given :-

A car runs at a constant speed on a circular track of radius 150 m taking 62.8 s on each lap.

To Find :-

Average speed

Average velocity

Solution :-

At first we need to find circumference of circle

Circumference of a circle = 2πr

Circumference = 2 × 3.14 × 150

Circumference = 2 × 314/100 × 150

Circumference = 2 × 314/2 × 3

Circumference = 314 × 3

Circumference = 942 m

Now,

Avg. Speed = Total distance/Total time

Avg. Speed = 942/62.8

Avg. Speed = 9420/628

Avg. Speed = 15 m/s

Since, starting point and stopping point is same. As, he had completed the round. Therefore, Average velocity is 0 m/s