Physics - Kinematics Question with Solution | TestHub

PhysicsKinematics1-DEasy2 minPYQ_2020

PhysicsEasynumerical

A helicopter takes off along the vertical with an acceleration $a = 3 m s^{- 2}$ and zero initial velocity. In a certain time $t_{1}$ , the pilot switches off the engine. At the point of take-off, the sound dies away in time $t_{2} = 30 s$ . Determine the velocity $v$ of the helicopter (in $m s^{- 1}$ ) at the moment when its engine is switched off, assuming that the velocity $c$ of sound is $320 m s^{- 1}$ .

Answer:

80.00

Solution:

$t_{2} = t_{1} + \frac{a t_{1}^{2}}{2 c}$

$t_{1} = \sqrt{{(\frac{c}{a})}^{2} + \frac{2 c}{a} t_{2}} - \frac{c}{a}$

$v = a t_{1} = a [\sqrt{{(\frac{c}{a})}^{2} + \frac{2 c t_{2}}{a}} - \frac{c}{a}]$

$= \sqrt{c^{2} + 2 a c t_{2}} - c = 80 m s^{- 1}$

Stream:NTA_ABHYASSubject:PhysicsTopic:KinematicsSubtopic:1-D

⏱ 2mℹ️ Source: PYQ_2020

Doubts & Discussion

Loading discussions...