swati and minal walk at a constant speed on two circular tracks of radius 20m and 40 m respectively.If both complete one circle at the same time,what is the relation between their walking speeds?
A. Speed of swati is equal to speed of minal
B. Speed of swati is twice the speed of minal
C. speed of Minal is twice the speed of swati
D. speed of minal is three times the speed of swati
Answers
Given :
Swati walks in a circle of radius 20m and minal walks in a circle of radius 40m.
Both complete one circle in same time.
To Find :
Relation between their speeds.
Solution :
❒ Speed is defined as the ratio of distance travelled to the time taken.
- It is a scalar quantity having only magnitude.
- SI unit : m/s
Distance covered by body after completing one round of circle will be equal to the perimeter of circle.
Let time taken by them to complete one round of circle be t
A. Speed of swati :
➛ v = 2πr / t
➛ v = 2π(20) / t
➛ v = 40π / t .......... (I)
B. Speed of minal :
➛ v' = 2πr' / t
➛ v' = 2π(40) / t
➛ v' = 80π / t .......... (II)
From equation (I) and (II),
➠ v / v' = (40π/t) / (80π/t)
➠ v / v' = 1 / 2
➠ v' = 2v
∴ (c) Speed of minal is twice the speed of swati.
Given :
Swati walks in a circle of radius 20m and minal walks in a circle of radius 40m.
Both complete one circle in same time.
To Find :
Relation between their speeds.
Solution :
❒ Speed is defined as the ratio of distance travelled to the time taken.
It is a scalar quantity having only magnitude.
SI unit : m/s
Distance covered by body after completing one round of circle will be equal to the perimeter of circle.
Let time taken by them to complete one round of circle be t..
A. Speed of swati :
➛ v = 2πr / t
➛ v = 2π(20) / t
➛ v = 40π / t .......... (I)
B. Speed of minal :
➛ v' = 2πr' / t
➛ v' = 2π(40) / t
➛ v' = 80π / t .......... (II)
From equation (I) and (II),
➠ v / v' = (40π/t) / (80π/t)
➠ v / v' = 1 / 2
➠ v' = 2v
∴ (c) Speed of minal is twice the speed of swati.