Physics - Kinematics Question with Solution | TestHub

PhysicsKinematics2-D & 3DEasy2 minPYQ_2020

PhysicsEasysingle choice

Two tall buildings are $40 m$ apart. With what speed must a ball be thrown horizontally from a window $145 m$ above the ground in one building, so that it will enter a window $22.5 m$ above from the ground in the other?

Options:

Answer:

Solution:

Given, $u_{x} = v$ and $u_{y} = 0$

Separating the motion in x and y directions

Using $x = u_{x} t + \frac{1}{2} a t^{2}$

$40 = v t$ (i)

$⟹ t = \frac{40}{v}$ (ii)

$y = h_{net} = 145 - 22.5$

Using $y = u_{y} t + \frac{1}{2} a t^{2}$

$122.5 = 0 + \frac{1}{2} \times 10 t^{2}$

$122.5 = 5 {(\frac{40}{v})}^{2}$

$v = 40 \sqrt{\frac{5}{122.5}} = 8 m s^{- 1}$

Subject:PhysicsTopic:KinematicsSubtopic:2-D & 3D

⏱ 2mℹ️ Source: PYQ_2020

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