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Science M.C.Q. [1 M]

Motion · Bihar Board (BSEB) STD 9 (BSEB - English Medium). 346 questions.

Questions · Page 4 of 7

M.C.Q. [1 M]

MCQ 1511 Mark
Is it possible for an object's velocity to increase while its acceleration decreases?
  • A
    No, this is impossible because of the way in which acceleration is defined.
  • B
    No, because if acceleration is decreasing the object will be slowing down.
  • C
    No, because velocity and acceleration must always be in the same direction.
  • ✓
    Yes, an example would be a falling object in a viscous medium, where the acceleration continuously decreases but velocity increases until a certain point.
Answer
Correct option: D.
Yes, an example would be a falling object in a viscous medium, where the acceleration continuously decreases but velocity increases until a certain point.
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MCQ 1521 Mark
A motorcycle is being driven at a speed of $20\ m/s$ when brakes are applied to bring it to rest five seconds. The deceleration produced in this case will be:
  • ✓
    $+4\ m/s^2$
  • B
    $-4\ m/s^2$
  • C
    $+0.25\ m/s^2$
  • D
    $-0.25\ m/s^2$
Answer
Correct option: A.
$+4\ m/s^2$

We have,
Initial velocity $= 20m/s$
Final velocity $= 0m/s$
Time taken $= 5 sec.$
So,
Deceleration = -Acceleration
$= \frac{-(0 - 20)}{5}$
$= 4\text{m/s}^2$

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MCQ 1531 Mark
When speed is stated along with its direction, it is called as:
  • ✓
    Velocity
  • B
    Acceleration
  • C
    Jerk
  • D
    None of these
Answer
Correct option: A.
Velocity
Velocity of a body is the speed of the body defined along with the direction.
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MCQ 1541 Mark
The slope of displacement$-$time graph being negative implies
  • ✓
    That the object moves towards the reference point
  • B
    That the object moves away from the reference point
  • C
    That the object is stationary
  • D
    None of these
Answer
Correct option: A.
That the object moves towards the reference point
Negative slope of a displacement-time graph indicates negative velocity.
Velocity is measured negative when a body moves towards the reference point.
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MCQ 1551 Mark
A stone is thrown vertically up from the ground. It reaches a maximum height of $50\ m$ in $10s$. After what time will it reach the ground from the maximum height?
  • A
    $5s$
  • ✓
    $10s$
  • C
    $20s$
  • D
    $25s$
Answer
Correct option: B.
$10s$

$\text{t}_\text{a}=\frac{\text{u}}{\text{g}}=10\text{s}$
same amount of time it will take to fall down

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MCQ 1561 Mark
A sprinter has to cover a total run of $100\ m$. She increases her speed from rest under a uniform acceleration of $1.0m/s^2$ up to three quarters of the total run and covers the last quarter him uniform speed. The time she takes to cover the first half, and to cover the second half of the run will be.
  • A
    $3.25s.$
  • ✓
    $4.28s.$
  • C
    $5.25s.$
  • D
    $6.25s.$
Answer
Correct option: B.
$4.28s.$
Here, total distance $= 100m$ For the first half of run,
distance $= 50m u = Om/s, a = m/s^2$ 
So by $\text{s}=\text{ut}+\frac{1}{2}\text{at}^{2}$
$50=0+\frac{1}{2}\times1\times\text{t}^{2}$
$\Rightarrow\text{t}=10\text{sec}$ At the end of $50m, v = u + at = 0 + 1 x 10 = 10m/s $ For the second half of run,
we calculate fors $= 25m$ first(uni formly accelerated motion)
Here $u = 10m/s, a = 1m/s^2$ 
So, $v^2 = u^2 + 2as = 100 + 2 \times 1 \times 25 = 150$
For time $t, v = u + at $
$\Rightarrow 12.24 = 10 + t 1 = 2.24sec$
For the last $25m$
$\text{t}=\frac{\text{distance}}{\text{speed}}$
$=\frac{25}{12.24}=2.04\text{sec}$
Hence time taken for the first half of run$(50m) = 10sec$
time taken for the second half of run$(50m) = 2.24 + 2.04 = 4.28sec$
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MCQ 1571 Mark
A body was initially moving with $10 \ m/ sec$ and it starts acceleration with $2 m/ sec^2$, the distance covered by it in $10$ sec will be
  • ✓
    $200\ m$
  • B
    $100\ m$
  • C
    $150\ m$
  • D
    $250\ m$
Answer
Correct option: A.
$200\ m$
$200\ m$
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MCQ 1581 Mark
The ratio of speed to the magnitude of velocity when the body is moving in one direction is:
  • A
    Less than one
  • B
    Greater than one
  • ✓
    Equal to one
  • D
    Greater than or equal to one
Answer
Correct option: C.
Equal to one
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MCQ 1591 Mark
Water drops fall at regular intervals from a roof at of $125\ m$ from the ground. At an instant when $11\ th$ drop is about leave the roof and $1st$ drop is at a height of $45\ m$ from the ground at that instant the dist of $10\ th$ drop from the roof is ($g=10 \mathrm{~m} / \mathrm{s}^2$)
  • A
    $0.40\ m$
  • B
    $0.20\ m$
  • ✓
    $0.80\ m$
  • D
    $1.2\ m$
Answer
Correct option: C.
$0.80\ m$
$0.80\ m$
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MCQ 1601 Mark
In which of the following cases of motion, the distance moved and the magnitude of displacement are equal?
  • ✓
    If the car is moving on straight road.
  • B
    If the car is moving on circular road.
  • C
    If the pendulum is moving to and fro.
  • D
    If a planet is moving around the sun.
Answer
Correct option: A.
If the car is moving on straight road.
The magnitude of displacement is equal to the distance travelled by a body when it travels in a straight line.
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MCQ 1611 Mark
Which of the following vehicles is undergoing a deacceleration?
  • A
    A car driving straight to the east on a road at a constant speed
  • B
    A truck rounding a corner at a constant speed
  • ✓
    A van slowing down as it approaches a stop sign
  • D
    None of these
Answer
Correct option: C.
A van slowing down as it approaches a stop sign
A object is said to have an acceleration if it changes its velocity either by increasing its speed, decreasing its speed or changing the direction of its velocity.
Since the car and the truck move with constant speed, thus they have zero acceleration.
But the van is slowing down its speed, thus it has deacceleration.
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MCQ 1621 Mark
Length of the straight line joining the initial to the final positions of a moving body is known as its:
  • A
    Distance
  • ✓
    Displacement
  • C
    Position
  • D
    None of these
Answer
Correct option: B.
Displacement
Displacement is the shortest distance joining initial and final points through a straight line
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MCQ 1631 Mark
Which parameters shown below are common between uniform circular motion and uniform linear motion:
  • A
    Velocity
  • ✓
    Speed
  • C
    Displacement
  • D
    Acceleration
Answer
Correct option: B.
Speed
In uniform circular motion, speed remains constant and even in a uniform linear motion, speed remains constant.
The direction of velocity in a uniform circular motion keeps changing as the particle moves along the curve
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MCQ 1641 Mark
If a displacement-time graph of an object is a straight line parallel to the time axis, the object is:
  • ✓
    Stationary
  • B
    Moving away from the reference point
  • C
    Moving towards the reference point
  • D
    Moving with an infinite velocity
Answer
Correct option: A.
Stationary
Displacement$-$time graph being parallel to the time axis, its slope is zero.
Slope of a displacement$-$time graph measures velocity.
So, velocity of the object is zero.
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MCQ 1651 Mark
What is the speed of a train which overtakes, a man walking at a speed of $5 \ km/ h$ in $30$ seconds, if the train is $274$ metres long?
  • A
    $51.88 \ km/ h$
  • B
    $47.88 \ km/ h$
  • ✓
    $37.88 \ km/ h$
  • D
    $21.67 \ km/ h$
Answer
Correct option: C.
$37.88 \ km/ h$
$37.88 \ km/ h$
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MCQ 1661 Mark
A car A is travelling on a straight level road with a uniform speed of $60\ km/h$. It is followed by another car $B$. Which is moving with a speed of $70\ km/h$. When the distance between them is $2.5\ km$, the car $B$ is given a deceleration of $20\ km/h2$. After how much time will $B$ catch up with $A?$
  • A
    $1h$
  • ✓
    $\frac{1}{2}\text{h}$
  • C
    $\frac{1}{4}\text{h}$
  • D
    $\frac{1}{8}\text{h}$
Answer
Correct option: B.
$\frac{1}{2}\text{h}$

$\text{S}_{\text{B}}=70\text{t}-\frac{1}{2}(20)\text{t}^{2}$
$\text{S}_{\text{A}}=60\text{t}$
$\text{S}_{\text{B}}-\text{S}_{\text{A}}=2.5\text{km}$
$70\text{t}-10\text{t}^{2}-60\text{t}=2.5$
$\Rightarrow10\text{t}^{2}-10\text{t}+2.5=0$
$\Rightarrow 4\text{t}^{2}-4\text{t}+1=0$
$\Rightarrow(2\text{t}-1)^{2}=0$
$\Rightarrow\text{t}=\frac{1}{2}\text{hr}=30\text{min}.$

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MCQ 1671 Mark
A motorcycle and a car start from rest at the same place at the same time and travel in the same direction.The motorcycle accelerates uniformly at $1 \mathrm{~m} / \mathrm{s}^2$ up to a speed of $36\ km/ h$ and the car at $0.5 \mathrm{~m} / \mathrm{s}^2$ up to a speed of $54\ km/ h$.Then the distance at which the car overtakes the cycle-
  • ✓
    $100\ m$
  • B
    $200\ m$
  • C
    $300\ m$
  • D
    $400\ m$
Answer
Correct option: A.
$100\ m$
$100\ m$
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MCQ 1681 Mark
$(1)$ In uniform circular motion, tangential acceleration is zero $(2)$ In uniform circular motion, velocity is constant.
  • A
    Both $1$ and $2$ are true and $2$ is correct explanation of $1$
  • B
    Both $1$ and $2$ are true and $2$ is not correct explanation of $1$
  • ✓
    $1$ is true and $2$ is false
  • D
    $1$ is false and $2$ is true
Answer
Correct option: C.
$1$ is true and $2$ is false
In uniform circular motion tangential acceleration is zero because angular velocity of motion is constant.
And the speed is uniform. But velocity of the particle in uniform circular motion keeps on changing.
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MCQ 1691 Mark
Pick out the wrong statement about retardation:
  • A
    Retardation is negative acceleration
  • B
    Retardation is rate of decrease of velocity with time
  • C
    $SI$ unit of retardation is $\mathrm{ms}^{-2}$
  • ✓
    Retardation is a scalar quantity
Answer
Correct option: D.
Retardation is a scalar quantity
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MCQ 1701 Mark
Direction of motion of a body is given by:
  • A
    Its speed
  • ✓
    Its velocity
  • C
    Both its speed and velocity
  • D
    Neither of its speed and velocity
Answer
Correct option: B.
Its velocity
Velocity is a vector.
So, it gives the magnitude of speed and the direction of motion of the body as well.
Speed being a scalar, does not give the direction of motion.
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MCQ 1711 Mark
What determine the nature of the path followed by the particle:
  • A
    Speed
  • B
    Velocity
  • C
    Acceleration
  • ✓
    None
Answer
Correct option: D.
None
Without initial velocity and acceleration path of the particle cannot be decided.
So at a time velocity and acceleration are required to determine the path followed by the particle.
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MCQ 1721 Mark
Choose the correct statement:
  • ✓
    Velocity determines direction of motion of a body
  • B
    Acceleration determines direction of motion of a body
  • C
    Both velocity and acceleration determine direction of motion of a body
  • D
    Neither velocity nor acceleration determine direction of motion of a body
Answer
Correct option: A.
Velocity determines direction of motion of a body
Velocity, being a vector, gives the direction of the change of position of a body.
Hence it determines the direction of motion of a body.
In contrast, acceleration doesn't need to relate to the direction of motion.
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MCQ 1731 Mark
To find the height of a building, a student is following the steps as given below. The sequence of the steps are:
  • A
    Drops a stone from the top of the building.
  • B
    Simultaneously, starts a clock.
  • ✓
    Stops the clock as the stone lands on the ground.
  • D
    Follows the relation $\text{h}=\frac{1}{5}\text{gt}^2.$
Answer
Correct option: C.
Stops the clock as the stone lands on the ground.
It is an Activity Question, so the steps that are followed to find the height of a building are simultaneously:
  1. Drops a stone from the top of the building.
  2. Simultaneously, starts a clock.
  3. Stops the clock as the stone lands on the ground.
  4. Follows the relation $\text{h}=\frac{1}{2}\text{gt}^2.$
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MCQ 1741 Mark
You can derive first equation of kinematics is from the formula of….
  • A
    Distance
  • B
    Speed
  • C
    Acceleration
  • D
    Velocity
Answer
  1. Acceleration
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MCQ 1751 Mark
You are sitting in a stationary car. There is a helium balloon tied to its floor. You accelerate and obviously feel like you are being pushed backwards (against the direction of your accelerations). The balloon.
  • A
    Will move forward.
  • B
    Will move backward.
  • C
    Will remain state.
  • D
    None of these.
Answer
  1. Will move forward.

Explanation:

The densest air in your passenger compartment is the ambient air. The least dense is your helium-filled balloon. When you accelerate, the ambient air will try to remain where it is and will appear to "slosh" toward the rear (if you can see the ambient air). Because the balloon has less inertia, it will be displaced by the heavier ambient air and will be forced forward in the passenger compartment.

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MCQ 1771 Mark
Which parameters shown below are common between uniform circular motion and uniform linear motion:
  • A
    Velocity
  • B
    Speed
  • C
    Displacement
  • D
    Acceleration
Answer
  1. Speed

Explanation:

In uniform circular motion, speed remains constant and even in a uniform linear motion, speed remains constant.

The direction of velocity in a uniform circular motion keeps changing as the particle moves along the curve

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MCQ 1781 Mark
Which of the quantities, speed or velocity gives the direction of motion of body:
  • A
    Speed
  • B
    Acceleration
  • C
    Velocity
  • D
    All of the above
Answer
  1. Velocity
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MCQ 1791 Mark
Which of the following vehicles is undergoing a deacceleration?
  • A
    A car driving straight to the east on a road at a constant speed
  • B
    A truck rounding a corner at a constant speed
  • C
    A van slowing down as it approaches a stop sign
  • D
    None of these
Answer
  1. A van slowing down as it approaches a stop sign

Explanation:

A object is said to have an acceleration if it changes its velocity either by increasing its speed, decreasing its speed or changing the direction of its velocity.

Since the car and the truck move with constant speed, thus they have zero acceleration.

But the van is slowing down its speed, thus it has deacceleration.

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MCQ 1801 Mark
Which of the following terms does not go well with the motion of a bus on a crowded road:
  • A
    Uniform velociity
  • B
    Variable velocity
  • C
    Variable acceleration
  • D
    Variable speed
Answer
  1. Uniform velociity

Explanation:

On a crowded road, depending on traffic conditions, the bus driver has to change its speed and direction of motion many times.

The driver will have to frequently apply brakes as well.

He might also have to accelerate the bus with different rates.

So, the velocity changes both by magnitude and direction.

Thus, uniform velocity is not attained in this case.

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MCQ 1811 Mark
Which of the following statements is correct for a particle travelling with a constant speed:
  • A
    Its position remains constant as time passes.
  • B
    It covers equal distances in unequal time intervals.
  • C
    Its acceleration is zero.
  • D
    It does not change its direction of motion.
Answer
  1. Its acceleration is zero.
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MCQ 1821 Mark
Which of the following statement is or are incorrect about the growing crops inside green-houses?
  • A
    A Greenhouse is built of any material through which sunlight can’t pass.
  • B
    The air continues to heat up because it gets confined within the greenhouse.
  • C
    To provide warmer temperature for growing fruit and vegetable plants.
  • D
    Green-house also protect it from high blowing wind and rodents.
Answer
  1. A Greenhouse is built of any material through which sunlight can’t pass.
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MCQ 1831 Mark
Which of the following statement is correct regarding velocity and speed of a moving body?
  • A
    Velocity of a moving body is always higher than its speed.
  • B
    Speed of a moving body is always higher than its velocity.
  • C
    Speed of a moving body is its velocity in a given direction.
  • D
    Velocity of a moving body is its speed in a given direction.
Answer
  1. Velocity of a moving body is its speed in a given direction.
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MCQ 1841 Mark
Which of the following situations is possible?
  • A
    An object can have acceleration, but constant velocity.
  • B
    The velocity of an object may be zero but acceleration is not zero.
  • C
    Distance and the magnitude of displacement are equal in circular motion.
  • D
    Average speed and the magnitude of average velocity are always equal in circular motion.
Answer
  1. The velocity of an object may be zero but acceleration is not zero.
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MCQ 1851 Mark
Which of the following situations are not possible?
  • A
    A body moving with constant acceleration but with zero velocity.
  • B
    A body moving horizontally with an acceleration in vertical direction.
  • C
    A body moving with a constant velocity in an accelerated motion.
  • D
    All of these.
Answer
  1. A body moving with a constant velocity in an accelerated motion.
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MCQ 1861 Mark
Which of the following quantity remains constant in a uniform circular motion:
  • A
    Velocity
  • B
    Speed
  • C
    Acceleration
  • D
    Both velocity and speed
Answer
  1. Speed

Explanation:

In a uniform circular motion, the direction of velocity changes but its magnitude remains constant, hence, speed remains constant in a uniform circular motion.

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MCQ 1871 Mark
Which of the following is true about distance and time.
  • A
    Distance and time are always directly proportional to each other.
  • B
    Distance and time are always indirectly proportional to each other.
  • C
    Distance and time are directly proportional when the velocity is constant.
  • D
    Distance and time are indirectly proportional when the velocity is constant.
Answer
  1. Distance and time are directly proportional when the velocity is constant.

Explanation:

$\text{Speed}=\frac{\text{Time}}{\text{Distance}} $

For uniform velocity, Distance ∝ Time

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MCQ 1881 Mark
Which of the following is not an example of a motion with a constant speed but variable velocity:
  • A
    A car moving at 80kmph on a straight road
  • B
    A car moving at 80kmph on a square track
  • C
    A car moving at 80kmph on a circular track
  • D
    A car moving at 80kmph on a zig-zag path
Answer
  1. A car moving at 80kmph on a straight road

Explanation:

A part from motion on straight road, for all other cases, direction of motion changes although the speed remains uniform.

So, speed remaining constant, velocity is variable for all other cases.

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MCQ 1891 Mark
Which of the following is not an example of acceleration:
  • A
    A person jogging at 3 m/ s along a winding path
  • B
    A car stopping at a stop sign
  • C
    A cheetah running 27 m/ s east
  • D
    A plane taking off
Answer
  1. A cheetah running 27 m/ s east
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MCQ 1901 Mark
Which of the following is most likely not a case of uniform circular motion?
  • A
    Motion of the earth around the sun.
  • B
    Motion of a toy train on a circular track.
  • C
    Motion of a racing car on a circular track.
  • D
    Motion of hours’ hand on the dial of a clock.
Answer
  1. Motion of a racing car on a circular track.
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MCQ 1911 Mark
Which of the following is/ are true about retardation:
  • A
    When velocity of a body decreases over time, the rate of change of velocity is known as retardation.
  • B
    Its SI unit is m/s2.
  • C
    It is the negative of acceleration
  • D
    All the above.
Answer
  1. All the above.

Explanation:

Retardation is opposite of acceleration.

In case of acceleration, velocity increases with time and in case of retardation, velocity decreases over time.

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MCQ 1921 Mark
Which of the following is a measurement of velocity:
  • A
    15 m east
  • B
    35 km/ h north
  • C
    18 m/ s2
  • D
    50 km/ h
Answer
  1. 35 km/ h north

Explanation:

Velocity is defined as speed plus direction so unit of velocity should be unit of speed plus direction

So option B has unit of speed km/h and direction as north.

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MCQ 1931 Mark
Which of the following is a correct measure of velocity?
  • A
    30s
  • B
    30m/s
  • C
    30 South
  • D
    30m/s, South
Answer
  1. 30m/s, South
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MCQ 1941 Mark
Which of the following defines displacement correctly:
  • A
    Change in position in a certain direction
  • B
    Change in position
  • C
    Length of path travelled
  • D
    None of these
Answer
  1. Change in position in a certain direction

Explanation:

Displacement is the linear distance between the initial and final positions.

So, it is change in position in a certain direction.

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MCQ 1951 Mark
Which is the most simple type of motion among the following?
  • A
    Motion in straight line.
  • B
    Motion in plane.
  • C
    Motion in space.
  • D
    Motion of projectile.
Answer
  1. Motion in straight line.
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MCQ 1961 Mark
When two bodies moves uniformly towards each her then they cross each other at the speed of 10m/s. If both the bodies move in the same direction, then they cross each other at the speed of 6m/s. The speed of both bodies are:
  • A
    8m/s, 2m/s
  • B
    8m/s, 4m/s
  • C
    6m/s, 2m/s
  • D
    6m/s, 4m/s
Answer
  1. 8m/s, 2m/s

Explanation:

Let the objects speed be x and y respectively, when moving towards each other:

x + y = 10 ...(1)

and, when moving in same direction

x - y = 6 ...(2)

now,

adding 1 and 2 we get

2x = 16m/s

x = 8m/s

and,

putting this in 1

y = 2m/s

The speed of the bodies is 8m/s2 and 2m/s2.

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MCQ 1971 Mark
When the distance an object travels is directly proportional to the time, it is said to travel with:
  • A
    Constant speed
  • B
    Zero velocity
  • C
    Constant acceleration
  • D
    Uniform velocity
Answer
  1. Constant speed

Explanation:

 

When the distance an object travels is directly proportional to time, it is said to travel with Constant Speed. 

$\text{Speed}=\frac{\text{distance travelled}}{\text{time}}$

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MCQ 1981 Mark
When speed is stated along with its direction, it is called as:
  • A
    Velocity
  • B
    Acceleration
  • C
    Jerk
  • D
    None of these
Answer
  1. Velocity

Explanation:

Velocity of a body is the speed of the body defined along with the direction.

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MCQ 1991 Mark
When an object is accelerated:
  • A
    Its direction must be constant
  • B
    Its velocity is necessarily changing
  • C
    Its velocity is constant
  • D
    Its speed is necessarily changing
Answer
  1. Its velocity is necessarily changing

Explanation:

Acceleration is the time rate of change of velocity.

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MCQ 2001 Mark
What is the speed of a train which overtakes, a man walking at a speed of 5 km/ h in 30 seconds, if the train is 274 metres long?
  • A
    51.88 km/ h
  • B
    47.88 km/ h
  • C
    37.88 km/ h
  • D
    21.67 km/ h
Answer
  1. 37.88 km/ h
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M.C.Q. [1 M] - Page 4 - Science STD 9 Questions - Vidyadip