1 A child completes a circular track of 200 m length in 10 seconds. Calculate a) speed, b) velocity.

2 A car travels 10 m in 5 seconds, 20 m in next 10 seconds and 30 m in the last 10 seconds. Find the average speed of the car.

3 A body moving in a circle of radius r covers 3/4th of the circle. Calculate the ratio of distance to displacment

4A train is moving with a velocity of 36 km/h. Find the distance travelled by the train in a) 1 hour, b) 1 minute.

1.

a. Speed

Distance = 200 m

Time = 10 s

Speed = 200/10 = 20 ms^-1

b. Velocity = 0 as net displacement completing a circular track is 0.

2.

Average speed = total distance covered / total time taken

  = (10 + 20 + 30)/(5 + 10 + 10)

  = 60 / 25

  = 2.4 ms^-1

3. Let the time taken = t 

Distance covered in completing ¾ of a circle = ¾×2πr

     = (3/2)πr  

Displacement = √(r² + r²)

  = r√2

Distance / displacement = (3/2)πr  / (r√2)

    = (3/2)π/√2

Distance : displacement = (3/2)π : √2

4. 

Here

Speed = 36 kmph

Distance = speed× time

1. Distance travelled in 1 hr = 36×1 = 36 km
2. Distance travelled in 1 min = 36×1/60 = 0.6 km