From a building two balls A and B are thrown with same speed

their velocities depend on their masses

Let the ball $A$ is thrown vertically upwards with speed $u$ and ball $B$ is thrown vertically downwards with the same speed $u$.
After reaching the highest point, $A$ comes back to its point of projection with the same speed $u$ in the downward direction. If $h$ be height of the building, then velocity of $A$ on reaching the ground is
$v^{2}_{A}=u^{2}+2gh$ or
$v_{A}=\sqrt{u^{2}+2gh}\,...\left(i\right)$
and that of $B$ on reaching the ground is
$v^{2}_{B}=u^{2}+2gh$ or
$v_{B}=\sqrt{u^{2}+2gh}\,...\left(ii\right)$
From eqns. $(i)$ and $(ii)$, we get $v_A = v_B$

Motion in a Plane

It is a vector quantity. A vector quantity is a quantity having both magnitude and direction. Speed is a scalar quantity and it is a quantity having a magnitude only. Motion in a plane is also known as motion in two dimensions.

Equations of Plane Motion

The equations of motion in a straight line are:

v=u+at

s=ut+½ at2

v2-u2=2as

Where,

v = final velocity of the particle
u = initial velocity of the particle
s = displacement of the particle
a = acceleration of the particle
t = the time interval in which the particle is in consideration

Ball A is thrown upwards from the building. During its downward journey when it comes back to the point of throw, its speed is equal to the speed of throw. So, for the journey of both the balls from point A to B .We can apply v2 – u2 = 2gh.As u, g, h are same for both the balls, vA = vB

Text Solution

` v_(B) gt v_(A)`` v_(A) = v_(B)`` v_(A) gt v_(B)` their velocities depend on their masses.

Answer : B

Solution : Ball `A` is thrown upwards from the building . During its downward journey when it comes back to the point of throw , its speed is equal to the speed of throw . So, for the journey of both the balls from point `A to B`. <br> We can apply `v^(2) - u^(2) = 2 gh`. <br> As `u, g, h`, are same for both the balls , ` v_(A) = v_(B) ` <br> <img src="https://d10lpgp6xz60nq.cloudfront.net/physics_images/JMA_MOT_C02_031_S01.png" width="80%">

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