MCQ Questions for Class 11 Engineering Physics Motion In A Plane Quiz 2

During projectile motion, the quantities that remain unchanged are :

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force and vertical velocity
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acceleration and horizontal velocity
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kinetic energy and acceleration
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acceleration and momentum

Select the odd one out (Velocity, Speed, Acceleration, Momentum)

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Momentum
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Velocity
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Speed
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Acceleration

When an object undergoes acceleration

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Its speed always increases
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Magnitude of velocity may remain constant
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It always falls towards the earth
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A force always acts on it

An object is thrown into space horizontally under the action of earth's gravity. Then the object is said to be a :

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projectile
0%
trajectory
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spaceship
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none of these

The path followed by a projectile is called its :

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trajectory
0%
range
0%
amplitude
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none of these

A vector

$\overrightarrow { V }$ is given in a rectangular coordinate system as

$V=4\overrightarrow { i } +3\overrightarrow { j }$
where

$\overrightarrow { i }$ and

$\overrightarrow { j }$ are unit vectors along

$x$ and

$y$ axis then the vector which is three times as long as

$\overrightarrow { V }$ is

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$12\overrightarrow { i } +9\overrightarrow { j }$
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$12\overrightarrow { i } +3\overrightarrow { j }$
0%
$4\overrightarrow { i } +9\overrightarrow { j }$
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$12\overrightarrow { i } -9\overrightarrow { j }$

Explanation

$\overrightarrow { V } =4\overrightarrow { i } +3\overrightarrow { j }$
then the vector which is three times as long as

$\overrightarrow { v }$ is

$3\overrightarrow { V } =12\overrightarrow { i } +9\overrightarrow { j }$

A merry-go-round is moving with a constant speed of

${12 ms^{-1}}$ , The girl sitting on it is

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At rest
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Moving with uniform velocity
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In accelerated motion
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Moving with no acceleration

Following is not a vector

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Linear momentum
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Electrical Field
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Kinetic Energy
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Acceleration

The horizontal distance travelled by a projectile is called its :

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range
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trajectory
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amplitude
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none of these

Which of the following physical quantities is different from others?

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Speed
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Distance
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Energy
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Average velocity

Which of the following motions is different from the rest?

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a ball thrown horizontally in air
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a bomb released from a flying aeroplane
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a javelin thrown by an athlete
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a bird flying in the air

When particles move in a circle at a constant speed then the motion is said to be

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Uniform circular motion
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Non uniform motion
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Projectile motion
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All

Fill in the blank:

Force is a __________quantity.

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Vector
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Scalar
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Tensor
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None

In the give velocity-time graph, acceleration equals

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$4 m/s^2$
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$5 m/s^2$
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$4.5 m/s^2$
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$3.5 m/s^2$

Explanation

Acceleration = slope of graph =

$dv/dt$

$=\Delta v / \Delta t$

$=10/2 = 5 \,m/s^2$

y-axis on velocity time graph represents

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Instantaneous velocity
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Average velocity
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Mean velocity
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None of the above

Why is velocity a vector whereas speed is a scalar quantity?

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Velocity has both magnitude and direction and speed has only magnitude
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Velocity has only magnitude and speed has both magnitude and direction
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Velocity has both magnitude and direction and speed has only direction
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Velocity has only direction and speed has both magnitude and direction

A vector quantity has

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Only magnitude
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Only direction
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Both magnitude and direction
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Neither magnitude nor direction

Friction is:

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a scalar quantity
0%
a vector quantity
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neither A or B
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either a scalar or a vector

A single velocity time graph can be drawn for

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1 dimension only.
0%
2 dimensions.
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3-dimensions.
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Can't be determined.

Which one from the following is Vector Quantity ?

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Work
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Weight
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Electric charge
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Distance

Identify the vector quantity from the following options?

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8 meters
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8 meters/second west
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8 meters/second
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all of the options are vector quantities
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8 seconds

A ball is thrown straight upward with initial velocity 15 m/s. Calculate acceleration of the ball at its highest point?

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0
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$\frac{1}{2}g$ , downward
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g, downward
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$\frac{1}{2}g$ , upward
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g, upward

Explanation

Throughout the motion of an object thrown up, regardless of the speed of object, the only force acting on the ball is

$mg$ downwards. Thus the acceleration of the object is

$g$ downwards always.

If two vectors have magnitudes of

$4.0\ m$ and

$7.0\ m$ , which of the following is NOT a possible magnitude for the resultant for the sum of the vectors?

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$3.0\ m$
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$4.0\ m$
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$5.0\ m$
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$11.0\ m$
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$12.0\ m$

Explanation

Maximum magnitude of the resultant vector,

$R_{max} = 4.0+7.0 = 11.0$ m

Minimum magnitude of the resultant vector,

$R_{min} = |4.0 - 7.0| = 3.0$ m

Thus range of magnitude of resultant vector,

$3.0$

$m\leq R \leq 11.0$

$m$

Hence, the correct answer is option E.

Identify the correct option . Distance and speed are:

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vector quantities.
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used to calculate acceleration.
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the same as displacement and velocity.
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inversely related to displacement and velocity.
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scalar quantities.

A woman travels over the top of a circular shaped hill on roller coaster so that she momentarily experiences the feeling of weightlessness at the very top of the hill. At this point. what is the woman's acceleration?

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$0 \,m/s^2 vertically \ only$
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$0 \,m/s^2 vertically\ and\ horizontally$
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$9.80\, m/s^2\ downward\ only$
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$9.80\,m/s^2 \ upward \ only$
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We need to know the radius of the truck and the speed of the coaster to answer this question.

During projectile motion when a particle reaches its highest point above the ground:

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Its velocity is instantaneously zero
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Its acceleration is instantaneously zero
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Its weight balances the force of air resistance
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The net force it feels is instantaneously zero
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None of the above

Explanation

A particle in projectile motion at its highest point above the ground-

(A) vertical component of the velocity becomes zero not the velocity.

(B) Its acceleration is not zero it is under the effect of gravitational acceleration

(D)It is experiencing a net force

$mg$ in downward direction ,not zero.

Therefore we have none of the above.

When a vector of magnitude 10 units is added to a vector of magnitude 5 units, the magnitude of the resultant vector will be:

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Exactly 5 units
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Exactly 10 units
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Exactly 15 units
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0 units, 10 units, or some value between them
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5 units, 15 units, or some value between them

Explanation

Given :

$|A_1| =10$ units

$|A_2| =5$ units

Maximum magnitude of resultant vector,

$A_{max} =|A_1|+|A_2| = 10 + 5 =15$ units

Minimum magnitude of resultant vector,

$A_{min} =|A_1-A_2| = 10 - 5 =5$ units

$\therefore$ Range of magnitude of resultant vector:

$5 \leq A_R \leq 15$ units

A centrifuge starts rotating from rest and reaches a rotational speed of

$8,000$ radians/sec in

$25$ seconds. Calculate the angular acceleration of the centrifuge?

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$160 radians/sec^{2}$
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$320 radians/sec^{2}$
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$640 radians/sec^{2}$
0%
$10,000 radians/sec^{2}$
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$20,000 radians/sec^{2}$

Explanation

Angular acceleration is given by ,

$\alpha=\Delta \omega/\Delta t$

given -

$\Delta \omega=8000 rad/s^{2} , t=25 s$

therefore ,

$\alpha=8000/25=320 radian/ s^{2}$

Two vectors X and Y are added together. Which of the following statements could be true?
I. The resultant magnitude is smaller than X.
II. The resultant magnitude is larger than Y.
III. The resultant direction is the same as either X or Y

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I only
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II only
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I and III only
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II and III only
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I, II, and III

Explanation

(i) If the angle between vectors

$X$ and

$Y$ is

$180^{o}$ , then resultant can be smaller than

$X$ .

(ii) If the angle between vectors

$X$ and

$Y$ is

$0^{o}$ , then resultant can be larger than

$Y$ .

(iii) If the angle between vectors

$X$ and

$Y$ is

$0^{o}$ or

$180^{o}$ , then the direction of resultant can be same as either

$X$ or

$Y$ .

Therefore, all statements could be true.

Identify the direction of the angular velocity vector for the second hand of a clock going from

$0$ to

$60$ seconds?

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Outward from the clock face
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Inward toward the clock face
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Upward
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Downward
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To the right

Explanation

Angular velocity

$\vec{v} = \vec{w} \times \vec{r}$

The second hand of a clock rotates in clockwise direction.

From figure, the direction of angular velocity is into the plane of page i.e inward toward the clock face (using Right-hand thumb rule).

Does the odometer of a car measure a scalar or a vector quantity?

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Scalar
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Vector
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Both
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Not scalar neither vector

The component of a vector

$\vec { r }$ along

$x$ -axis will have a maximum value if:

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$\vec { r }$ along +ve $x$ -axis
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$\vec { r }$ along +ve $y$ -axis
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$\vec { r }$ along -ve $y$ -axis
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$\vec { r }$ makes an angle of ${45}^{o}$ with the $x$ -axis

Explanation

Component of vector

$r$ in

$x$ direction,

$|r_x| = r\cos\theta$

where

$\theta$ is the angle between

$\vec{r}$ and

$x$ axis

$|r_x|$ is maximum, thus

$r\cos\theta$ is maximum.

This is possible only when

$\cos\theta = 1$

$\implies$

$\theta = 0^o$

Hence,

$\vec{r}$ is along +ve x-axis.

Force is a

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Vector
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Scalar
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None of above these
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Both A and B

Mass is a _____ quantity.

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scalar
0%
vector
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tensor
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None of them

Two vectors A and B have equal magnitudes. If magnitude of A + B is equal to n times the magnitude of A - B, then the angle between A and B is

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${\cos}^{-1}\begin{pmatrix}\dfrac{n-1}{n+1}\end{pmatrix}$
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${\cos}^{-1}\begin{pmatrix}\dfrac{n^2-1}{n^2+1}\end{pmatrix}$
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${\sin}^{-1}\begin{pmatrix}\dfrac{n-1}{n+1}\end{pmatrix}$
0%
${\sin}^{-1}\begin{pmatrix}\dfrac{n^2-1}{n^2+1}\end{pmatrix}$

Explanation

$\left| A+B\right|=n\left| A-B\right|$

$\implies (A^2+B^2+2ABcos\theta)=n^2(A^2+B^2-2ABcos\theta)$

It is given that

$A+B$

Hence

$cos\theta=\dfrac{n^2-1}{n^2+1}$

$\implies \theta=cos^{-1}(\dfrac{n^2-1}{n^2+1})$

The set containing only vector quantities is :

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Displacement, Acceleration, Speed, Force
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Force, Velocity, Distance, Acceleration
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Acceleration, Velocity, Time, Displacement
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Displacement, Velocity, Acceleration, Force

At the top of the trajectory of a projectile, thrown at an angle of projection

$\theta < {90}^{o}$ , its

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Velocity is zero
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Velocity is parallel to the direction of acceleration
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Velocity is anti-parallel to the direction of acceleration
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Velocity is perpendicular to the direction of acceleration

Among the following, the vector quantity is

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Pressure
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Gravitational potential
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Stress
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Impulse
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Distance

In a uniform circular motion, the angle between the velocity and acceleration is :

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$0$
0%
$45^o$
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$60^o$
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$75^o$
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$90^o$

Explanation

In a circular motion, the angel between the velocity and acceleration is

$90^o$ .

Point

$(4, 0)$ lies on ________.

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$\vec {XO}$
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$\vec {YO}$
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$\vec {OX}$
0%
$\vec {OY}$

Explanation

$\vec {XO}$ is positive x-axis, so

$(4, 0)$ lies on it.

If the points

$A$ and

$B$ are

$\left( 1,2,-1 \right)$ and

$\left( 2,1,-1 \right)$ respectively, then

$\vec { AB }$ is

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$\hat { i } +\hat { j }$
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$\hat { i } -\hat { j }$
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$2\hat { i } +\hat { j } -\hat { k }$
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$\hat { i } +\hat { j } +\hat { k }$

Explanation

$\vec{ AB } =$

$\left < 2-1, 1-2, -1+1 \right >$

$= \left < 1,-1, 0 \right >$

$\therefore\quad\vec{AB} =$

$\hat{ i } - \hat{ j}$

The set containing only scalar quantities is :

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Speed, Temperature, Displacement, Time
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Time, Force, Distance, Speed
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Speed, Time, Temperature, Distance
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Distance, Time, Temperature, Acceleration

State whether true or false :

Scalar is represented by magnitude only.

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True
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False

Select the wrong statement about pressure:

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Pressure is a scalar quantity
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Pressure is always compressive in nature
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Pressure at a point is same in all directions
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None of these

Explanation

A) Pressure is a scalar quantity

$\vec{F}=P\vec{A}$

As force and area are vectors and pressure is the proportionality constant

Also, pressure is defined as force per unit area

$\therefore$ It is area vector that gives it direction.

B) Pressure is not always compressive

Blowing a balloon expands it.

$\therefore$ Internal pressure is expansive.

C) This statement is derived from pascal's law.

1126741_824027_ans_fc9ee841b8144c53b7ad77708ccd7555.jpeg

If a body moving in a circle of radius

$10m$ is covering a displacement of

$20m$ , in

$10s$ , then the speed of the body can be

0%
$n\pi$ , where $n=1,3,5.....$
0%
$n\pi$ , where $n=1,2,3,....$
0%
$\dfrac{n\pi}{2}$ , where $n=1,3,5....$
0%
$\dfrac{n\pi}{2}$ , where $n=1,2,3....$

Explanation

When it covers a displacement of 20 m, it ends up at the diametrically opposite point from where it initially started. But as we do not know that whether the body has covered half a circle or one half or two and half and so on..... the distance it has covered will be

$\dfrac{2\pi r}{2}\times n$ where

$n=1\ or\ 3\ or\ 5\ ..........2x+1$

so the speed of the body will be

$\dfrac{10n\pi}{10\ s}=n\pi \ m/s$ where

$n$ can be 1,3,5......

A 60-kg person on a merry-go round is travelling in a circle with a radius of

$3 \ m$ at a speed of

$6 \ m/s$ . What is the magnitude of the net force experienced by this person?

0%
$zero$
0%
$60N$
0%
$180N$
0%
$600N$
0%
$720N$

Explanation

It is given that

Mass of person $m=60\,Kg$

The person is travelling in a circular path of radius $r=3\,m$

Velocity of person is $v=6\,m/s$

Centripetal acceleration is

${{a}_{c}}=\dfrac{{{v}^{2}}}{r}$

${{a}_{c}}=\dfrac{{{6}^{2}}}{3}=12\,m/{{s}^{2}}$

Force

$F=ma$

$=60\times 12$

$=720\,N$

A line passes through the points whose position vectors

$\hat { i } +\hat { j } -2\hat { k }$ and

$\hat { i } -3\hat { j } +\hat { k }$ . Then the position vector of a point on it at a unit distance from the first point is

0%
$\dfrac { 1 }{ 5 } \left( 5\hat { i } +\hat { j } -7\hat { k } \right)$
0%
$\dfrac { 1 }{ 5 } \left( 5\hat { i } +9\hat { j } -13\hat { k } \right)$
0%
$\left( \hat { i } -4\hat { j } +3\hat { k } \right)$
0%
$\left( \hat { i } +4\hat { j } +3\hat { k } \right)$

Explanation

Let points of the position vector

$\hat i + \hat j - 2\hat k$ and

$\hat i - 3\hat j + \hat k$ are

$A(1,1-2)$ and

$(1,-3,1)$

$AB=\sqrt{(1-1)^2+(1+3)^2+(-2-1)^2}=5$

Required points which divide

$AB$ in ratio

$1:4$

The required position vector of the point

$=\dfrac{1 \times (\vec i -3 \vec j + \vec k)+4(\vec i+\vec j-2 \vec k)}{1+4}=\dfrac{1}{5}(5 \vec i + \vec j -7 \vec k)$

The linear velocity of a point on the equator is nearly( Radius of the earth is 64km)

0%
800 km/hr
0%
1600 km/hr
0%
3200 km/hr
0%
6400 km/hr

The component of a vector r along x-axis will have maximum value if:

0%
r is along positive y-axis
0%
r is along positive x-axis
0%
r makes an angle of 45 $^{\circ}$ with the y-axis
0%
r is along negative y-axis

Explanation

The component should be at an angle of

$0^{\circ}$ from the axis given here and thus the component of the vector along x-axis will have the maximum value when r is along x-axis.

There are three forces acting on an object : 6 N to the left ,5 N to the right , and 3 N to the left.What is the net force acting on the object?

0%
4 N
0%
4 N left
0%
4 N right
0%
8 N left
0%
None of above

Explanation

Take right side is toward positive, x-axis.

${{\vec{F}}_{1}}=6(-\hat{i})\,N,\,{{\vec{F}}_{2}}=5\hat{i}\,N\,\,\,\,\,and\,\,\,{{\vec{F}}_{3}}=3(-\hat{i})\,N$

${{\vec{F}}_{net}}={{\vec{F}}_{1}}+{{\vec{F}}_{2}}+{{\vec{F}}_{3}}=-6\hat{i}+5\hat{i}-3\hat{i}=4\left( -\hat{i} \right)\,N$

Hence, force is $4\,N$ toward left.

CBSE Questions for Class 11 Engineering Physics Motion In A Plane Quiz 2 - MCQExams.com

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Practice Class 11 Engineering Physics Quiz Questions and Answers

CBSE Questions for Class 11 Engineering Physics Motion In A Plane Quiz 2 - MCQExams.com

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Practice Class 11 Engineering Physics Quiz Questions and Answers

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