CBSE Questions for Class 11 Engineering Physics Motion In A Plane Quiz 3 - MCQExams.com

A fly wheel rotating at 600 rev/min is brought under uniform deceleration and stopped after 2 minutes, then what is angular deceleration in $$rad/sec^2$$?
  • $$\frac{\pi}{6}$$
  • $$10 \pi$$
  • $$\frac{1}{12}$$
  • 300
AT the point of the trjectory of a projectile, the acceleration is then
  • Maximum.
  • Minimum
  • Zero
  • g
What is the rage of a projectile thrown with velocity $$98 \,m/sec$$ with angle $$30^o$$ from horizontal?
  • $$490\sqrt{3}$$ meter
  • $$9800\sqrt{3}$$ meter
  • $$245\sqrt{3}$$ meter
  • $$100\sqrt{3}$$ meter
A curved section of road is banked for a speed v. if there is no friction between road and tyres of the car , then :
  • car is more likely to slip at speeds higher than V 
  • car cannot remain in static equilibrium on the curved section
  • car will not slip when moving with speed v
  • none of the above
If $$\overrightarrow{A}$$ and $$\overrightarrow{B}$$ are two unit vectors and the angle between them is $$90^o$$. Then $$\dfrac{1-\overrightarrow{A}. \overrightarrow{B}}{1+ \overrightarrow{A}. \overrightarrow{B}}is$$
  • 1
  • 2
  • 0
  • 3
$$\vec{r}  = \vec{x}\hat{i}+\vec{y}\hat{j}$$ is the equation of:
  • $$yoz$$ plane
  • a straight line joining the points $$\vec{i}$$ and $$\vec{j}$$
  • $$zox$$ plane
  • $$xoy$$ plane
A ball is thrown across a flat field.
Which statement describes the motion of the ball, when the effects of air resistance are ignored?

1648464_8b828aedd8b648508bbf2eb7da6b9204.png
  • The ball lands with the same velocity at which it is thrown
  • The horizontal component of acceleration is constant throughout the motion
  • The horizontal and vertical components of acceleration are both zero at the highest point of
    the motion
  • The horizontal and vertical components of velocity are both zero at the highest point of the
    motion
If $$\vec{a}$$ be the position vector whose tip is (5,-3), find the coordinates of a point B such that $$ \vec{AB} = \vec{a},$$ the coordinates of A being (4,-1).
  • (9, -4)
  • (-9, -4)
  • (9, 4)
  • none of these
find the coordinate of the tip of the position vector which is equivalent to $$ \vec{AB}$$, where the coordinates of A and B are (-1, 3) and (-2, 1) respectively.
  • (+1,+2)
  • (+1,-2)
  • (-1,+2)
  • (-1,-2)
If the position vectors of the points $$A(3,4),B(5, -6)$$ and $$C(4,-1)$$ are $$ \vec{a}, \vec{b}, \vec{c}$$ respectively, compute $$ \vec{a}+2\vec{b}-3\vec{c}. $$
  • $$ -5\hat{i}-1\hat{j} $$
  • $$ \hat{i}-5\hat{j} $$
  • $$ \hat{i}+5\hat{j} $$
  • none of these
A particle of mass M is moving in a circle with constant speed v , between two position at the ends of a diameter, the particle's
  • Momentum changes by mv
  • kinetic energy changes by$$ 1/2 mv^2 $$
  • Momentum changes by 2 mv
  • Kinetic energy changes by $$ mv^2 $$
A ball falls from a table top with initial horizontal speed $$V_o$$. In the absence of air resistance, which of the following statement is correct.
  • The vertical component of the acceleration changes with time
  • The horizontal component of the velocity does not changes with time
  • The horizontal component to the acceleration is no zero and finite
  • The time taken by the ball to touch the ground depends on $$V_0$$
  • The vertical component of the acceleration varies with time
Surface area is
  • Scalar
  • Vector
  • Neither scalar not vector
  • Both scalar and vector
Which of the following is a scalar quantity
  • Displacement
  • Electric field
  • Acceleration
  • Work
Assertion :A physical quantity cannot be called as a vector if its magnitude is zero
Reason :A vector has both, magnitude and direction.
  • Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
  • Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
  • Assertion is correct but Reason is incorrect
  • Both Assertion and Reason are incorrect
  •  assertion is false but reason is true
Three forces are acted on a body. Their magnitudes are $$3\ N, 4\ N$$ and $$5\ N$$. Then
  • The acceleration of body must be zero
  • The acceleration of body may be zero
  • The acceleration of the body must not be zero
  • None of the above
Write true or false for the following statement:
A quantity which can be completely specified by magnitude as well as direction is called a scalar quantity
  • True
  • False
Which of the following physical quantity is scalar?
  • Mass
  • Force
  • Impulse of force
  • Momentum
If $$a = 0.72$$ and $$r = 0.24$$, then the value of $$t_r$$ is 
  • $$0.02$$
  • $$0.04$$
  • $$0.4$$
  • $$0.2$$
A particle is moving in a circle in a radius $$r$$ with a constant speed $$v$$ . The change in velocity after the particle has traveled a distance equal to $$(\dfrac{1}{8})^{th}$$of the circumference of the circle is:
  • zero
  • $$0.5\; V$$
  • $$0.765 \;V$$
  • $$0.125 \;V$$
If a particle moves in a circle, describing equal angles in equal intervals of time, the velocity vector:
  • Remains constant.
  • Changes in magnitude.
  • Changes in direction.
  • Changes both in magnitude and direction.
Match List $$I$$ with List $$II$$ for a projectile
            
  List$$ - I$$                                                                                                                                                                                                              List $$- II$$  
$$(a)$$ For two angles $$2\theta $$ and $$2(90 - \theta )$$ with same magnitude of velocity of projection
$$(e)\ \dfrac{P\hat {i}\cdot P\hat{i}}{g}$$
$$(b)$$ Equation of parabola of a projectile $$y = PX -QX^{2}$$
$$(f)$$ Maximum height$$ = 25\%$$ of $$\dfrac{P^{2}}{Q}$$
$$(c)$$ Radius of curvature of path of a body projected with velocity $$ \left[P\hat{i}+Q\hat{j}\right] ms^{-1}$$ at highest point
$$(g)$$ Range $$=$$ Maximum height
$$(d)$$ Angle of projection
$$\theta =\tan ^{-1} (4)$$
$$(h)$$ Range is same
The correct match is :
  • $$ a\rightarrow f,b\rightarrow h, c\rightarrow g,d\rightarrow e.$$
  • $$a\rightarrow h,b\rightarrow f, c\rightarrow e,d\rightarrow g $$ .
  • $$a\rightarrow e,b\rightarrow g, c\rightarrow f,d\rightarrow h $$.
  • $$ a\rightarrow e,b\rightarrow g, c\rightarrow h,d\rightarrow f $$.
For a projectile, the physical quantities which remain constant are:
  • vertical component of velocity and kinetic energy.
  • potential energy and kinetic energy.
  • acceleration and horizontal component of velocity 
  • potential energy and acceleration.
Angle between velocity and acceleration vectors in the following cases are given below. Match the correct pairs.
     List I                               List  II            
a) Vertically projected
body
e) $$90^{0}$$
b) For freely dropped
body
f) changes from
point to point
c) For projectile
g) zero
d) In uniform circular
motion		h) $$180^{0}$$
  • $$a\rightarrow h,b\rightarrow g,c\rightarrow f,d\rightarrow e.$$
  • $$a\rightarrow f,b\rightarrow g,c\rightarrow h,d\rightarrow e$$.
  • $$a\rightarrow e,b\rightarrow f,c\rightarrow h,d\rightarrow g$$.
  • $$a\rightarrow g,b\rightarrow h,c\rightarrow e,d\rightarrow f.$$
A ball is thrown with a velocity $$u$$ making an angle '$$\theta$$' with the horizontal. Its velocity vector is normal to initial velocity vector $$u$$ after a time interval of
  • $$\dfrac{u \sin \theta} {g}$$
  • $$\dfrac {u} {g \cos \theta}$$
  • $$\dfrac{u} {g \sin \theta}$$
  • $$\dfrac{4 \cos \theta}{g}$$
At the maximum height of a projectile, the velocity and acceleration are
  • parallel to each other
  • antiparallel to each other
  • perpendicular to each other
  • inclined to each other at $$45^{0}$$
A particle moves in a plane with a constant acceleration in a direction different from the initial velocity. The path of the particle is:
  • a straight line
  • an arc of circle
  • a parabola
  • an ellipse
Study the following

   List - I                                                 List - II
 
a) Horizontal motion of a projectile
e) zero velocity
b) Freely falling body                                
f) retarded motion from
a small height
c) Parachutist
g) uniform descending down
 acceleration.
d) Maximum height of a body thrown
vertically up
h) uniform velocity


The correct match is
  • $$a\rightarrow g,b\rightarrow f,c\rightarrow h,d\rightarrow e,g$$.
  • $$a\rightarrow h,b\rightarrow g,c\rightarrow f,d\rightarrow e,g$$.
  • $$a\rightarrow e,b\rightarrow h,c\rightarrow f,d\rightarrow g,c$$.
  • $$a\rightarrow f,b\rightarrow e,c\rightarrow g,d\rightarrow h$$.
A ball is thrown with a velocity of $$8\  ms^{-1}$$ making an angle of $$60^{o}$$ with the horizontal. It's velocity will be perpendicular to the direction of initial velocity of projection after a time of ($$g= 10  ms^{-2}$$)
  • $$\dfrac{1.6}{\sqrt{3}}s$$
  • $$\dfrac{4}{\sqrt{3}}s$$
  • $$4\sqrt{3}  s$$
  • $$0.8\sqrt{3}  s$$
A body is projected with a velocity $$u$$ at an angle of  $$60^{o}$$ to the horizontal. The time after which it will be moving in a direction of $$30^{o}$$ to the horizontal is
  • $$\dfrac{1}{\sqrt3} \dfrac{u}{g} $$
  • $$\dfrac{\sqrt{3}u}{g}$$
  • $$\dfrac{\sqrt{3}u}{2g}$$
  • $$\dfrac{2u}{\sqrt{3}g}$$
Assertion (A): In the motion of projectile the horizontal component of velocity remains constant 
Reason (R) : The force on the projectile is the gravitational force which acts only in the vertically downward direction
  • A and R are correct and R is the correct explanation of A
  • A and R are correct and R is not the correct explanation of A
  • A is true and R is false 
  • A is false and R is true
The distances covered by a particle thrown in a vertical plane, in horizontal and vertical directions at any instant of time 't' are x $$=$$ 3t and $$ y =4t - 5t^{2}$$.The acceleration due to gravity is
  • $$8 m/s^{2}$$
  • $$9 m/s^{2}$$
  • $$10 m/s^{2}$$
  • $$16 m/s^{2}$$
A body is projected with a velocity of $$20  m/s$$ making an angle $$45^{o}$$ with the horizontal. Its path (in m) is represented by $$(g = 10 \ ms^{-2})$$
  • $$y=x-\dfrac{x^{2}}{20}$$ 
  • $$y=x-\dfrac{x^{2}}{40}$$ 
  • $$y = \sqrt{3}x-\dfrac{x^{2}}{40}$$ 
  • $$y = \dfrac{x}{\sqrt{3}}-\dfrac{x^{2}}{40}$$ 
A circular disc is rotating about its own axis at constant angular acceleration. If its angular velocity increases from $$210\ rpm$$ to $$420\ rpm$$ during $$21$$ rotations then the angular acceleration of disc is :
  • $$5.5\ rad/s^{2}$$
  • $$11\ rad/s^{2}$$
  • $$16.5\ rad/s^{2}$$
  • $$22\ rad/s^{2}$$
A stationary wheel starts rotating about its own axis at a constant angular acceleration. If the wheel completes $$50$$ rotations in the first $$2\ s$$, then the number of rotations made by it in the next $$2\ s$$ is:
  • $$75$$
  • $$100$$
  • $$125$$
  • $$150$$
If the angle of projection is $$60^{o}$$, the height of the projectile when it has travelled a distance $$ \dfrac{3R}{4}$$ is ($$R$$ is the range)
  • $$\dfrac{3\sqrt{3}R}{16}$$
  • $$\dfrac{2}{3}R$$
  • $$\dfrac{\sqrt{3}R}{16}$$
  • $$\dfrac{4}{5}R$$
For a projectile, the ratio of maximum height reached to the square of the time of flight is $$(g=10  ms^{-2})$$
  • $$5:4$$
  • $$5:2$$
  • $$5:1$$
  • $$10:1$$
A stationary wheel starts rotating about its own axis with an angular acceleration of $$ 5.5\ rad / s^{2}$$. To acquire an angular velocity $$420$$ revolutions per minute, the number of rotations made by the wheel is:
  • $$14$$
  • $$21$$
  • $$28$$
  • $$35$$
A motor car is moving in a circular path with uniform speed, $$V$$. Suddenly the car rotates through an angle $$\theta $$. Then, the magnitude of change in its velocity is 
  • $$2V\cos\dfrac{\theta }{2}$$
  • $$2V\sin\dfrac{\theta }{2}$$
  • $$2V\tan\dfrac{\theta }{2}$$
  • $$2V\sec\dfrac{\theta }{2}$$
A:The sum and difference of two vectors will be equal in magnitude when two vectors are perpendicular to each other.
B:The sum and difference of two vectors will have the same direction, when the vectors have unequal magnitudes but are in the same direction.
  • Both A and B are true
  • A is true but B is false
  • B is true but A false
  • Both A and B are false
A wheel has a speed of $$1200$$ revolutions per minute and is made to slow down at a rate of $$4\ radians/s^{2}$$. The number of revolutions it makes before coming to rest is:
  • $$143$$
  • $$272$$
  • $$314$$
  • $$722$$
lf the initial velocity of a body is $$\mathrm{V}_{1}$$ and final velocity is $$\mathrm{V}_{2}$$ and the angle between $$\mathrm{V}_{1}$$ and $$\mathrm{V}_{2}$$ is $$\phi$$, then the change in velocity is:
  • $$\mathrm{V}_{2}-\mathrm{V}_{1}$$
  • $$\sqrt{\mathrm{V}_{2}^{2}+\mathrm{V}_{1}^{2}}$$
  • $$\sqrt{\mathrm{V}_{1}^{2}+\mathrm{V}_{2}^{2}-2\mathrm{V}_{1}\mathrm{V}_{2}\cos\phi}$$
  • $$\sqrt{\mathrm{V}_{1}^{2}+\mathrm{V}_{2}^{2}+2\mathrm{V}_{1}\mathrm{V}_{2}\cos\phi}$$
In circular motion if $$\bar{v}$$ is velocity vector, $$\bar{a}$$ is acceleration vector, $$\bar{r}$$ is instantaneous position vector, $$ \bar{p}$$ is momentum vector and $$\bar{\omega}$$ is angular velocity of particle, then:
  • $$\bar{v}$$, $$\bar{\omega}$$, $$\bar{r}$$ are mutually perpendicular
  • $$\bar{p}$$, $$\bar{v}$$, $$\bar{\omega}$$ are mutually perpendicular
  • $$\bar{r} \times \bar{v} = 0$$ and $$\bar{r} \times \bar{\omega} = 0$$
  • $$\bar{r}.\bar{v} = 0$$ and $$\bar{r}.\bar{\omega} = 0$$
A force: $${F}=(6\hat{i} - 8\hat{j} + 10\hat{k})\ N$$ produces an acceleration of $$1\ m/s^{2}$$ in a body. The mass of body would be:
  • $$200\  Kg$$
  • $$20\  Kg$$
  • $$10\sqrt{2}\  Kg$$
  • $$6\sqrt{2}\  Kg$$

Out of the following options, the resultant of which pair cannot be 4N?
  • 2N and 2N
  • 3N and 8N
  • 2N and 6N
  • 4N and 8N
Assertion(A): Electric current and velocity of light both have direction as well as the magnitude but still they are not considered as vectors.
Reason(R): Electric current and velocity of light do not follow laws of vector addition.
  • Both A and R are true and the R is correct explanation of the A
  • Both A and R are true, but R is not correct explanation of the A
  • A is true, but the R is false
  • A is false, but the R is true
A wheel having a radius of $$10\  cm$$ is coupled by a belt to another wheel of radius $$30\  cm$$. 1st wheel increases its angular speed from rest at a uniform rate of 1.57 $$rad/s^2$$. The time for the 2nd wheel to reach a rotational speed of $$100\  rev/min$$ is (assume that the belt does not slip):
  • $$20 \ s$$
  • $$10\  s$$
  • $$1.5\  s$$
  • $$15 \ s$$
A circular disc is rotating about its own axis at uniform angular velocity $$\omega$$. The disc is subjected to uniform angular retardation by which its angular velocity is decreased to $$\dfrac{\omega}{2}$$  during $$120$$ rotations. The number of rotations further made by it before coming to rest is:
  • $$120$$
  • $$60$$
  • $$40$$
  • $$20$$
The length of a seconds hand in a watch is $$1$$ cm. The change in its velocity in $$15$$ s is
  • $$0\ cm/s$$
  • $$\displaystyle \dfrac{\pi}{30\sqrt{2}}\ cm /s$$
  • $$\dfrac{\pi}{30}\ cm / s$$
  • $$\displaystyle \dfrac{\pi}{30}\sqrt{2}\ cm / s$$
Two projectiles of same mass and with same velocity are thrown at an angle 60 & 30 with the horizontal, then which quantity will remain same :
  • Time of flight
  • Horizontal range of projectile
  • Max height acquired
  • All of them
0:0:1


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