Tag: physics

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Questions Related to physics

Multiple choice physics simple harmonic motion representing shm with circular motion shm as projection of circular motion simple harmonic motion (shm) as a projection of uniform circular motion

The period of a particle it is $8s$. At $t=0$ it is at the mean position. The ratio of the distance covered by the particle in first second and second will be

  1. $\cfrac { \sqrt { 2 } -1 }{ \sqrt { 2 } } $

  2. $\cfrac { 1 }{ \sqrt { 2 } } $

  3. $\cfrac { 1 }{ \sqrt { 2 } -1 } $

  4. $\left[ \sqrt { 2 } -1 \right] $
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$x=A\sin\omega t$

$T= 8 sec$
$\dfrac{2\pi}{\omega}=8 sec$
$\omega=\dfrac{2\pi}{8}=\dfrac{\pi}{4}$
$x=A\sin \dfrac{\pi}{4} t$ ,At $t=1 sec$
$x _1=\dfrac{A}{\sqrt2}$ ,At $t=2sec$
$x _2=A$
Required ration $=\dfrac{x _1}{x _2-x _1}=\dfrac{1/\sqrt2}{1-\dfrac{1}{\sqrt2}}=\dfrac{1}{\sqrt2-1}$

Multiple choice physics simple harmonic motion representing shm with circular motion shm as projection of circular motion simple harmonic motion (shm) as a projection of uniform circular motion

Sunlight of intensity 1.3 kW m–2 is incident normally on a thin convex lens of focal length 20 cm. Ignore the energy loss of light due to the lens and assume that the lens aperture size is much smaller than its focal length. The average intensity of light, kW m–2, at a distance 22 cm from the lens on the other side is _________. 

  1. $ 130 $

  2. $120 \ $

  3. $ 170$

  4. $160 $
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Multiple choice physics simple harmonic motion representing shm with circular motion shm as projection of circular motion simple harmonic motion (shm) as a projection of uniform circular motion

Simple harmonic motion is the projection of uniform circular motion on the

  1. $x$- axis

  2. $y$- axis

  3. reference circle

  4. any diameter of reference circle.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Simple harmonic motion is the projection of uniform circular motion on any diameter of reference circle.

Multiple choice force in shm oscillations oscillation and waves physics

Which one of the following equations of motion represents simple harmonic motion?

  1. Acceleration =$-k _0x+k _1x^2$

  2. Acceleration =$-k(x+a)$

  3. Acceleration =$k(x+a)$

  4. Acceleration =$kx$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Simple harmonic motion (SHM) is defined by a restoring force (or acceleration) that is directly proportional to the negative displacement from the equilibrium position, expressed as a = -kx. Option B represents this form, where the equilibrium position is shifted by 'a'.

Multiple choice force in shm oscillations oscillation and waves physics

The mass of particle executing S.H.M is 1 gm.If its periodic time is $\pi $ seconds, the value of force constant is:-

  1. 4 dynes/cm

  2. 4 N/cm

  3. 4 N/m

  4. 4 dynes/m
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Given, mass $m=1 gm$; time period $T=\pi$ sec

The angular frequency $\omega=\frac{2\pi}{T}=\frac{2\pi}{\pi}=2$
As $\omega=\sqrt{k/m}$  where ($k$ is the force constant),
$k=m\omega^2=(1 gm)(2)^2=4$ dynes/cm

Multiple choice force in shm oscillations oscillation and waves physics

A particle of mass 1kg is moving in a S.H.M with an amplitude of 0.02m and a frequency of 60Hz. The maximum force acting on the particle is :

  1. $2.88 \times 10^{3}$N

  2. $1.44 \times 10^{3}$N

  3. $5.67 \times 10^{3}$N

  4. $0.75 \times 10^{3}$N
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$f = 60\ Hz$
$w = 2\pi f = 120\pi \  rad/sec$
$F = mw^{2}A$
$= 1 \ kg \times 14400 \times \pi ^{2} \times  0.02$
$= 2.88 \times 10^{3}N$

Multiple choice force in shm oscillations oscillation and waves physics

In case of force oscillations of a body

  1. driving force is constant throughout.

  2. driving force is to be applied only momentarily.

  3. driving force has to be periodic and continuous.

  4. driving force is not required.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In case of force oscillations of a body driving force has to be periodic and continuous.

Multiple choice force in shm oscillations oscillation and waves physics

A student says that he had applied a force $F= -k\sqrt {x}$ on a particle and the particle moves in simple harmonic motion. He refuses to tell whether $k$ is a constant or not. Assume that he has worked only with positive $x$ and no other force acted on the particle.

  1. As $x$ increases $k$ increases

  2. As $x$ increases $k$ decreases

  3. As $x$ increases $k$ remains constant

  4. The motion cannot be simple harmonic
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Given that the motion of the particle is Simple Harmonic Motion.

$F=-m\omega^2 x$

The force applied by the student is given by, 

$F=-\dfrac{-k}{x}$

If the motion is S.H.M., then both will be equal.

So,

$\dfrac{-k}{-x}=m\omega^2 x$

$k=m\omega^2 x^2$

This means, if $x$ increases, then $k$ also increases.

So the correct answer is option a.
Multiple choice force in shm oscillations oscillation and waves physics

The force of a required to row a boat at velocity is proportional to square of its speed of v km/ h requires 4 KW, how many does a seepd of 2V km/h required 

  1. 8 kW

  2. 16 kW

  3. 32kw

  4. 76kw
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Here $F\propto V^{2}$
$P = F\times V$
$\propto V^{2}\times V = V^{3}$
$\therefore \dfrac{P _{1}}{P _{2}}=\dfrac{V _{1}^{3}}{V _{2}^{3}}=\left(\dfrac{V}{2V}\right)^{3}=\dfrac{1}{8}$
$\therefore P _{1}=4kw$
$P _{2}=8\times 4= 32kw$
$\therefore P _{2}= 32kw$
Multiple choice force in shm oscillations oscillation and waves physics

A body is executing SHM. If the force acting on the body is 6N when the displacement is 2 cm, then the force acting on the body when the displacement is 3 cm in newton is:

  1. $ 6 $ N

  2. $9$ N

  3. $4$ N

  4. $\sqrt{6} $ N
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
$ F = m w^{2}x$
$ \dfrac{F _{1}}{F _{2}} = \dfrac{x _{1}}{x _{2}}$
$ F _{2}  = \dfrac{3}{2}\times 6 \ N  =  9 \ N$