Download App

2. motion in straight line — Physics STD 11 Science — Question

Rajasthan BoardEnglish MediumSTD 11 SciencePhysics2. motion in straight line1 Mark
MCQ
An elevator car whose floor to ceiling distance is $27\,m$ starts ascending with a constant acceleration of $1.2\,m / s ^2$. After $2\,s$ of the start, a bolt falls from the ceiling of the car. The free fall time of the bolt is $\left(g=9.8\,m / s ^2\right)$
  • A
    $\sqrt{\frac{2.7}{9.8}}\,s$
  • B
    $\sqrt{\frac{5.4}{9.8}}\,s$
  • C
    $\sqrt{\frac{5.4}{8.6}}\,s$
  • ✓
    $\sqrt{\frac{5.4}{11}}\,s$
✓

Answer

Correct option: D.
$\sqrt{\frac{5.4}{11}}\,s$
d
(d)

Relative to lift

$u_r =0$

$a_r =(9.8+1.2)=11\,m / s ^2$

$s_r =\frac{1}{2} a_r t^2$

$2.7 =\frac{1}{2} \times 11 \times t^2$

or $t=\sqrt{\frac{5.4}{11}}\,s$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "M.C.Q (1 Marks)" from 2. motion in straight line→2. motion in straight line — all question types→Physics STD 11 Science question papers→Rajasthan Board STD 11 Science question papers→Rajasthan Board question paper generator→

Similar questions

Which of the following types of motion can be used for describing the motion of a car on a straight road?
→
A boy playing on the roof of a $10\, m$ high building throws a ball with a speed of $10\,m/s$ at an angle of $30^o$ with the horizontal. How far from the throwing point will the ball be at the height of $10\, m$ from the ground ?  $\left[ {g = 10\,m/{s^2},\sin \,{{30}^o} = \frac{1}{2},\cos \,{{30}^o} = \frac{{\sqrt 3 }}{2}} \right]$
→
According to $C.E.$ van der Waal, the interatomic potential varies with the average interatomic distance $(R)$ as
→
When a guitar string is sounded with a $440\, Hz$ tuning fork, a beat frequency of $5\, Hz$ is heard. If the experiment is repeated with a tuning fork of $437\,Hz$, the beat frequency is $8\, Hz$. The string frequency $(Hz)$ is
→
A ball of mass $4\, kg$, moving with a velocity of $10\, ms ^{-1}$, collides with a spring of length $8\, m$ and force constant $100\, Nm ^{-1}$. The length of the compressed spring is $x\, m$. The value of $x$, to the nearest integer, is ........ .
→
A car is moving around a tree in a circular path. What can be said about the average velocity?
→
The velocity $v$ of a particle moving along $x$-axis varies with its position $(x)$ as $v=\alpha \sqrt{x}$; where $\alpha$ is a constant. Which of the following graph represents the variation of its acceleration (a) with time $(t)$ ?
→
Given below are two statements. One is labelled as Assertion A and the other is labelled as Reason $R$.

Assertion $A$ : If $dQ$ and $dW$ represent the heat supplied to the system and the work done on the system respectively. Then according to the first law of thermodynamics $d Q=d U-d W$.

Reason $R :$ First law of thermodynamics is based on law of conservation of energy.

In the light of the above statements, choose the correct answer from the option given below :

→
The bob of a simple pendulum (mass m and length $ l$) dropped from a horizontal position strikes a block of the same mass elastically placed on a horizontal frictionless table. The K.E. of the block will be
→
Let $\theta$ denote the angular displacement of a simple pendulum oscillating in a vertical plane. If the mass of the bob is m, then tension in the string is mg $\cos\theta$
→