A ball is released from top of a tower of height h meters. It takes T seconds to reach ground. posit

English

Gujarati

Hindi

2.Motion in Straight Line

hard

A ball is released from the top of a tower of height $h$ meters. It takes $T$ seconds to reach the ground. What is the position of the ball in $\frac {T}{3}$ seconds

A

$\frac{h}{9}$ meters from the ground

B

$\frac{7h}{9}$ meters from the ground

C

$\frac{8h}{9}$ meters from the ground

D

$\frac{17h}{18}$ meters from the ground

(AIEEE-2004)

Solution

(c) $\;\;h = ut + \frac{1}{2}g{t^2} \Rightarrow h = \frac{1}{2}g{T^2}$

After $\frac{T}{3}$ seconds, the position of ball,

$h' = 0 + \frac{1}{2}g{\left( {\frac{T}{3}} \right)^2} = \frac{1}{2} \times \frac{g}{9} \times {T^2}$

$h' = \frac{1}{2} \times \frac{g}{9} \times {T^2}$$ = \frac{h}{9}\,m$ from top

Position of ball from ground $ = h – \frac{h}{9} = \frac{{8\;h}}{9}\,m.$

Standard 11

Physics

Share

Similar Questions

A player throws a ball upwards with an initial speed of $29.4 \;m s^{-1}$. What is the direction of acceleration during the upward motion of the ball?

easy

A parachutist after bailing out falls $20\,\,m$ without friction. When parachute opens, it decelerates at $2\,\,m/s^2.$ He reached the ground with a speed with a speed of $4\,\,m/s.$ At what height, did he bail out ?……$m$

medium

Two balls $A$ and $B$ are thrown with same velocity $u$ from the top of a tower. Ball $A$ is thrown vertically upwards and the ball $B$ is thrown vertically downwards. If $t_A$ and $t_B$ are the respective times taken by the balls $A$ and $B$ respectively to reach the ground, then identify the correct statement

medium

Two bodies of masses $1 kg$ and $5 kg$ are dropped gently from the top of a tower. At a point $20 cm$ from the ground, both the bodies will have the same

easy

A player throws a ball upwards with an initial speed of $29.4\; m s^{-1}$. To what height does the ball rise and after how long (in second) does the ball return to the player's hands $?$ (Take $g=9.8 \;m s^{-2}$ and neglect air resistance).

medium