Download App

3.2 , motion in plane — Physics STD 11 Science — Question

Rajasthan BoardEnglish MediumSTD 11 SciencePhysics3.2 , motion in plane1 Mark
MCQ
Two particles are simultaneously projected in opposite directions horizontally from a given point in space, where gravity $g$ is uniform. If $u_1$ and $u_2$ be their initial speeds, then the time $t$ after which their velocities are mutually perpendicular is given by
  • ✓
    $\frac{\sqrt{u_1 u_2}}{g}$
  • B
    $\frac{\sqrt{u_1^2+u_2^2}}{g}$
  • C
    $\frac{\sqrt{u_1\left(u_1+u_2\right)}}{g}$
  • D
    $\frac{\sqrt{u_2\left(u_1+u_2\right)}}{g}$
✓

Answer

Correct option: A.
$\frac{\sqrt{u_1 u_2}}{g}$
a
(a)

$v _1 \perp v _2$

$\therefore \quad v _1 \cdot v _2=0$

$\text { or }\left(u_1 \hat{ i }-g t \hat{ j }\right) \cdot\left(-u_2 \hat{ i }-g t \hat{ j }\right)=0$

$\therefore \quad g^2 t^2=u_1 u_2$

$\text { or }$

$t=\frac{\sqrt{u_1 u_2}}{g}$

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 3.2 , motion in plane→3.2 , motion in plane — all question types→Physics STD 11 Science question papers→Rajasthan Board STD 11 Science question papers→Rajasthan Board question paper generator→

Similar questions

A tube of length $50\,cm$ is filled completely with an incompressible liquid of mass $250\,g$ and closed at both ends. The tube is then rotated in horizontal plane about one of its ends with a uniform angular velocity $x \sqrt{ F }$ rad $s ^{-1}$. If $F$ be the force exerted by the liquid at the other end then the value of $x$ will be$....$
→
If $L,\,C$ and $R$ represent inductance, capacitance and resistance respectively, then which of the following does not represent dimensions of frequency
→
The angle between two vectors $4\hat i + 3\hat j + \hat k$ and $-3\hat i + 2\hat j + 6\hat k$ is ....... $^o$
→
A body of mass $5 \,kg$ is moving with velocity of $\vec{v}=(2 i+6 \hat{j}) \,m / s$ at $t=0 \,s$. After time $t =2 \,s$, velocity of body is $(10 \hat{i}+6 \hat{j})$, then change in momentum of body is ......... $kg m / s$
→
Average pressure pav is defined as:
→
A block of mass $10\, kg$ starts sliding on a surface with an initial velocity of $9.8\, ms ^{-1}$. The coefficient of friction between the surface and bock is $0.5$. The distance covered by the block before coming to rest is: [use $g =9.8\, ms ^{-2}$ ].........$m$
→
A rectangular block of mass m and area of cross section A floats in a liquid of density $\rho$ If it is given a small vertical displacement from equilibrium, it undergoes oscillations with a time period T, then:
→
A block of mass $m$ is pulled along a horizontal surface by applying a force at an angle $\theta $ with the horizontal. The friction coefficient between the block and surface is $\mu$. If the block travels at a uniform velocity , then work-done during its displacement $d$ is
→
A tuning fork sends sound waves in air. If the temperature of the air increases, which of the following parameters will change?
  1. Displacement amplitude.
  2. Frequency.
  3. Wavelength.
  4. Time period.
→
The power (P) of an engine lifting a mass of 100kg upto a height of 10m in 1 min is:
→