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प्रश्न
Solve the following problem.
An aeroplane has a run of 500 m to take off from the runway. It starts from rest and moves with constant acceleration to cover the runway in 30 sec. What is the velocity of the aeroplane at the take-off?
उत्तर
Given: Length of runway (s) = 500 m, t = 30 s
To find: Velocity (v)
Formulae:
1. s = ut + `1/2 "at"^2`
2. v = u + at
Calculation:
As the plane was initially at rest, u = 0 From formula (i),
500 = `0 + 1/2 xx "a" xx (30)^2`
∴ 500 = 450 a
∴ a = `10/9` m/s2
From formula (ii),
v = 0 + `10/9 xx 30`
∴ v = `100/3 "m/s" = (100/3 xx 18/5)"km/hr"`
∴ v = 120 km/hr
The velocity of the aeroplane at the take off is 120 km/hr.
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