Download App

5.work,energy,power and collision — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysics5.work,energy,power and collision1 Mark
MCQ
$A$ force exerts an impulse $I$ on a particle changing its speed from $u$ to $2u$. The applied force and the initial velocity are oppositely directed along the same line. The work done by the force is
  • A
    $\frac{3}{2}{\text{I}}\,{\text{u}}$
  • ✓
    $\frac{1}{2}{\text{I}}\,{\text{u}}$
  • C
    $I \,u$
  • D
    $2\, I\, u$
✓

Answer

Correct option: B.
$\frac{1}{2}{\text{I}}\,{\text{u}}$
b
$\mathrm{I}=\Delta \mathrm{P}$

$\mathrm{I}=2 \mathrm{mu}-(-\mathrm{mu})$

$\mathrm{I}=3 \mathrm{mu} \ldots(\mathrm{i})$

According to work energy theorem

$\mathrm{W}=\Delta \mathrm{T}$

$\mathrm{W}=\mathrm{T}_{\mathrm{f}}-\mathrm{T}_{\mathrm{i}}$

$\mathrm{W}=\frac{1}{2} \mathrm{m}(2 \mathrm{u})^{2}-\frac{1}{2} \mathrm{m}(-\mathrm{u})^{2}$

$\mathrm{W}=\frac{1}{2} \mathrm{m}\left(4 \mathrm{u}^{2}\right)-\frac{1}{2} \mathrm{mu}^{2}$

$\mathrm{w}=\frac{3 \mathrm{mu}^{2}}{2}$         $...(ii)$

From equation $(i)$ and $(ii)$

$\mathrm{W}=\frac{1}{2} \mathrm{Iu}$

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 5.work,energy,power and collision→5.work,energy,power and collision — all question types→Physics STD 11 Science question papers→Gujarat Board STD 11 Science question papers→Gujarat Board question paper generator→

Similar questions

Water waves produced by a motor boat sailing in water are:
→
The velocity $v$ (in $cm/\sec $) of a particle is given in terms of time $t$ (in sec) by the relation $v = at + \frac{b}{{t + c}}$ ; the dimensions of $a,\,b$ and $c$ are
→
The kinetic energy of a body of mass $3 \,kg$ and momentum $2 \,N-s$ is
→
A string fixed at its both ends vibrates in $5\,\,loops$  as shown in the figure  

The total number of nodes and antinodes are respectively

→
The number of molecules per unit volume in the sample is $20.$ The mass of each molecule is $10-20\ kg.$ The mean of speed squared is $4\ m^2/s^2$. What is the value of internal energy of the gas? Assume volume of container is $0.02m^3$.
→
A mass m is suspended from a spring of length l and force constant $K$. The frequency of vibration of the mass is ${f_1}$. The spring is cut into two equal parts and the same mass is suspended from one of the parts. The new frequency of vibration of mass is ${f_2}$. Which of the following relations between the frequencies is correct
→
A particle executes simple harmonic oscillation with an amplitude $a.$ The period of oscillation is $T.$ The minimum time taken by the particle to travel half of the amplitude from the equilibrium position is 
→
A bullet moving with a speed of $100$ $m{s^{ - 1}}$can just penetrate two planks of equal thickness. Then the number of such planks penetrated by the same bullet when the speed is doubled will be
→
In an octagon $ABCDEFGH$ of equal side, what is the sum of $\overrightarrow{ AB }+\overrightarrow{ AC }+\overrightarrow{ AD }+\overrightarrow{ AE }+\overrightarrow{ AF }+\overrightarrow{ AG }+\overrightarrow{ AH }$ if, $\overrightarrow{ AO }=2 \hat{ i }+3 \hat{ j }-4 \hat{ k }$
→
A batsman hits back a ball straight in the direction of the bowler without changing its initial speed of $12 \;m/ s$.

If the mass of the ball is $0.15 \;kg$, determine the impulse (in $N\;s$) imparted to the ball. (Assume linear motion of the ball)

→