Question

A car completes the first lap of its race with 100km/h.With what speed shall it move in second lap so that average speed of both laps becomes 200km/h

Answer 1

Answer:-

Given:-

• Average speed between the initial speed and the final speed = 200 km h^-1
• Initial speed = 100 km h^-1

To Find:-

Final speed of the car.

_______________...

We know,

vₐᵥ = (v + u)/2

[Mean method]

where,

• vₐᵥ = Average speed,
• v = Final speed &
• u = Initial speed.

Let the final speed be = v

∴ (v + 100 km/h)/2 = 200 km/h

➵ 2[v/2 + 50 km/h] = 200 km/h

[Since 2(v/2) = v; (50 km/h)2 = 100 km/h]

➵ v/2 + 50 km/h = 200 km/h

➵ v/2 = (200 - 50) km/h

➵ v/2 = 150 km/h

➵ v = (2)(150 km/h)

➵ v = 300 km/h

∴ The speed of the car on the second lap was equal to 300 km/h.