Download App

4.1 , newtons laws of motion — Physics STD 11 Science — Question

Rajasthan BoardEnglish MediumSTD 11 SciencePhysics4.1 , newtons laws of motion1 Mark
MCQ
An elevator car, whose floor to ceiling distance is equal to $2.7 \,m$, starts ascending with constant acceleration of $1.2 \;ms^{-2}$. $2 \,sec$ after the start, a bolt begins fallings from the ceiling of the car. The free fall time of the bolt is.........$s$
  • A
    $\sqrt {0.54} $
  • B
    $\sqrt 6$
  • ✓
    $0.7$
  • D
    $1$
✓

Answer

Correct option: C.
$0.7$
c
(c) $t = \sqrt {\frac{{2h}}{{(g + a)}}} $

$ = \sqrt {\frac{{2 \times 2.7}}{{(9.8 + 1.2)}}} = \sqrt {\frac{{5.4}}{{11}}} = \sqrt {0.49} = 0.7\sec $

As $u = 0$ and lift is moving upward with acceleration

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 4.1 , newtons laws of motion→4.1 , newtons laws of motion — all question types→Physics STD 11 Science question papers→Rajasthan Board STD 11 Science question papers→Rajasthan Board question paper generator→

Similar questions

A gas is enclosed in a closed pot. On keeping this pot in a train moving with high speed, the temperature of the gas
→
A proton and an electron are accelerated by the same potential difference. Let $\lambda_\text{e}$ and $\lambda_\text{p}$ denote the de Broglie wavelengths of the electron and the proton respectively.

  1. $\lambda_\text{e}=\lambda_\text{p}.$

  2. $\lambda_\text{e}<\lambda_\text{p}.$

  3. $\lambda _\text{e}>\lambda_\text{p}.$

  4. The relation between $\lambda_\text{e}$, and $\lambda_\text{p}$ depends on the accelerating potential difference.

→
Dimensions of strain are
→
The angle turned by a body undergoing circular motion depends on time as $\theta = {\theta _0} + {\theta _1}t + {\theta _2}{t^2}$. Then the angular acceleration of the body is
→
Neglecting the air resistance, the time of flight of a projectile is determined by
→
A small bob tied at one end of a thin string of length $1\, m$ is describing a vertical circle so that the maximum and minimum tension in the string are in the ratio $5: 1 .$ The velocity of the bob at the height position is ............. $m / s$ (Take $\left.g=10 \,m / s ^{2}\right)$
→
A particle of mass $2\, kg$ is on a smooth horizontal table and moves in a circular path of radius $0.6\, m$. The height of the table from the ground is $0.8\, m$. If the angular speed of the particle is $12\, rad\, s^{-1}$, the magnitude of its angular momentum about a point on the ground right under the centre of the circle is ........ $kg\, m^2\,s^{-1}$
→
Energy of all molecules of a monoatomic gas having a volume $V$ and pressure $P$ is $\frac{3}{2}PV$. The total translational kinetic energy of all molecules of a diatomic gas as the same volume and pressure is
→
Four mole of hydrogen, two mole of helium and one mole of water vapour form an ideal gas mixture. What is the molar specific heat at constant pressure of mixture?
→
A composition string is made up by joining two strings of different masses per unit length $\rightarrow \mu$ and $4\mu$ . The composite string is under the same tension. A transverse wave pulse $: Y = (6 mm) \,\,sin\,\,(5t + 40x),$ where $‘t’$ is in seconds and $‘x’$ in meters, is sent along the lighter string towards the joint. The joint is at $x = 0$. The equation of the wave pulse reflected from the joint is
→