Question

A toy car travels from A to B at a constant speed of 20 Km/h and immediately returns to A at a constant speed v.If the average speed of the car is 24 Km/h,then v is​

Answer 1

As the object starts from A and stops at A , displacement = 0 .

v = displacement/time

=0/time

=0 m/s

Answer 2

Answer:

30 kmph

Explanation:

Let the distance between A and B be "S"

Time taken by toy car to travel from A to B = t₁

• t₁ = Distance / Speed
• t₁ = S/20

Time taken to travel by toy car to travel from B to A = t₂

• t₂ = Distance / Speed
• t₂ = S/v

Average speed = Total Distance / Total time

24 = (2S) / (t₁ + t₂)

24 = (2S) / (S/20 + S/v)

24 = 2 / (1/20 + 1/v)

24/2 = 1 / (1/20 + 1/v)

12 = 1 / (1/20 + 1/v)

1/12 = 1/20 + 1/v

1/v = 1/12 - 1/20

1/v = 1/4 × [1/3 - 1/5]

1/v = 1/4 × [5/15 - 3/15]

1/v = 1/4 × 2/15

1/v = 2/60

1/v = 1/30

v = 30 kmph