CBSE Questions for Class 9 Physics Motion Quiz 12 - MCQExams.com

The following figure gives the movement of an object. Select the correct statement from the given choices.
1698440_fc72250ad0334e0da2e55b7cb0b09c31.png
  • The total distance travelled by the object is $$975\ m$$
  • The maximum acceleration of the object is $$2\ ms^{-2}$$
  • The maximum deceleration happened between $$25th$$ and $$85th$$ seconds
  • The object was at rest between $$10th$$ and $$15th$$ seconds
  • At $$40th$$ second, the speed of object was decelerating
Speed is to velocity as:
  • Centimetre is to metre
  • Force is to torque
  • Velocity is to acceleration
  • Distance is to displacement
The height of the body after 5 s from the ground is $$(g=9.8m/s^2).$$
  • 8 m
  • 12 m
  • 18 m
  • 24 m
The speed-time graph of a body is straight line parallel to time axis. The body has:
  • uniform acceleration
  • uniform speed
  • variable speed
  • variable acceleration
Two bodies , one held $$ 1 \, m $$ vertically above the other , are released simultaneously and fall freely under gravity . After $$ 2 $$ second , the relative separation of the bodies will be : 
  • $$ 4.9\, m $$
  • $$ 9.8\,m $$
  • $$ 19.6\,m $$
  • $$1 \,m $$
A bus travels 54 km in 90 minutes. The speed of the bus is?
  • 0.6m/s
  • 10m/s
  • 5.4m/s
  • 3.6 m/s
If we denote speed by $$S$$, distance by $$D$$ and time by $$T$$ the relationship these equation is? 
  • $$S= D \times T $$
  • $$T= \frac {S}{D}$$
  • $$S = \frac {1}{T} \times D$$
  • $$ S= \frac {T}{D}$$
Four cars $$A, B, C$$ and $$D$$ are moving on a levelled road. Their distance versus time graphs are shown in Fig $$8.2$$. Choose the correct statement
1791219_f299220a4fa34f0493f264105f45bd05.png
  • Car $$A$$ is faster than car $$D$$.
  • Car $$B$$ is the slowest.
  • Car $$D$$ is faster than car $$C$$.
  • Car $$C$$ is the slowest.
A body is thrown vertically upward with velocity $$u$$, the greatest height $$h$$ to which it will rise is,
  • $$\dfrac{u}{g}$$
  • $$\dfrac{u^{2}}{2g}$$
  • $$\dfrac{u^{2}}{g}$$
  • $$\dfrac{u}{2g}$$
The correct symbol to represent the speed of an object is
  • $$5m/s$$
  • $$5mp$$
  • $$5 m/ sec^{-1} $$
  • $$5 s/m$$

A black paper absorbs light of all the colours and reflects none.
  • True
  • False
State whether the following statement is true or false.
In a uniform circular motion, the speed continuously changes because of the direction of motion changes.
  • True
  • False
$$18\ km\ h^{-1}$$ is equal to :
  • $$10\ ms^{-1}$$
  • $$5\ ms^{-1}$$
  • $$18\ ms^{-1}$$
  • $$1.8\ ms^{-1}$$
A body falls from rest, its velocity at the end of first second is $$ ( g =  32 \,ft / s^2) $$ 
  • $$ 16 \, ft / s $$
  • $$ 32 \, ft / s $$
  • $$ 64 \, ft / s $$
  • $$ 24 \, ft / s $$
A body thrown with an initial speed of $$ 96\, ft / sec $$  reaches the ground after $$ ( g = 32 ft / sec^2 )$$
  • $$ 3 \,sec $$
  • $$ 6 \,sec $$
  • $$ 12 \,sec $$
  • $$ 8 \,sec $$
The variation of velocity of a particle with time moving along a straight line is shown in the figure. The distance traveled by the particle in $$4\ s$$ is :
1812909_46f7fdeb6d8a4de2ba2bbd445dde73db.png
  • $$ 60\,m $$
  • $$ 55 \,m $$
  • $$ 25 \,m $$
  • $$ 30\,m $$
Time taken by an object falling from rest to cover the height of $$ h_1 $$ and $$ h_2 $$ is respectively $$ t_1 $$ and $$ t_2 $$ then the ratio of $$ t_1 $$ to $$ t_2 $$ is 
  • $$ h_1 : h_2 $$
  • $$ \sqrt{h_1} : \sqrt{h_2} $$
  • $$ h_1 : 2 h_2 $$
  • $$ 2h : h $$
An object moving in upward direction opposite to the gravitational force of earth performs
  • accelerated motion
  • motion with constant velocity
  • oscillations
  • retarded motion
The horizontal straight line obtained from the distance-time graph is related to which of the following velocity ?
  • Zero velocity
  • Constant velocity
  • Increasing velocity
  • Decreasing velocity
Four alternatives are given to each of the following incomplete statements/questions, choose the right answer.
Uniform circular motion is called continuously accelerated motion mainly because 
  • Direction of motion changes
  • Speed remains the same
  • Velocity remains the same
  • Direction of motion does not change
Figure represents the displacement-time graph of motion of two cars A and B. Find the velocities of car A and car B.
202877.png
  • $$v_A = 20 km h^{-1}, v_B = 10 km h^{-1}$$
  • $$v_A = 10 km h^{-1}, v_B = 20 km h^{-1}$$
  • $$v_A = 20 km h^{-1}, v_B = 40 km h^{-1}$$
  • $$v_A = 40 km h^{-1}, v_B = 20 km h^{-1}$$
In the figure, the displacement time graph of a body is shown at different time-intervals. Calculate the velocity of the body as it moves for
$$(i)\ 0 \ to\ 5 s$$,
$$(ii)\ 5 s \ to\ 7 s$$ and
$$(iii)\ 7 s\ to\ 9 s$$.
202837_c87365c105284a2c85d044372a22f89a.png
  • $$(i) \ 1.2 m s^{-1}
    (ii)\  0 m s^{-1}
    (iii) \ 1 m s^{-1}$$
  • $$(i) \ 0.6 m s^{-1}
    (ii) \ 0 m s^{-1}
    (iii)\  2 m s^{-1}$$
  • $$(i) \ 0 m s^{-1}
    (ii) \ 0.6 m s^{-1}
    (iii) \ 4 m s^{-1}$$
  • $$(i)\  0.3 m s^{-1}
    (ii) \ 1 m s^{-1}
    (iii)\  1.2 m s^{-1}$$
Two masses of mass $$40\ gm $$ and $$30\ gm $$ are connected across a pulley with the help of light string, then the acceleration of the system is 
  • $$ 4.9 m/s^{2}$$
  • $$2.94 m/s^{2}$$
  • $$1.4 m/s^{2}$$
  • $$9.8 m/s^{2}$$
A lift performs the first part of its ascent with uniform acceleration, $$a$$, and the remaining with uniform retardation, $$2a$$. If, $$t$$, is the time of ascent, the depth of the shaft is
  • $$\displaystyle \dfrac{{at}^{2}}{4}$$
  • $$\displaystyle \dfrac{{at}^{2}}{3}$$
  • $$\displaystyle \dfrac{{at}^{2}}{2}$$
  • $$\displaystyle \dfrac{{at}^{2}}{8}$$
Using the table given below where the values of velocity at the end of t seconds for a body under linear motion are given
$$V (m\:s^{-1})$$
0

6
12
24
30
36
42
$$t (s)$$
0

2
4
8
10
12
14
What can be concluded about the motion of the body?
  • It moves with uniform speed.
  • It moves with uniform motion
  • It moves with uniform velocity
  • It moves with uniform acceleration
What is the minimum height above the ground at which the rocketeer should catch the student?
  • $$92.1\ m$$
  • $$460.9\ m$$
  • $$78.8\ m$$
  • $$82.3\ m$$
A smooth track of incline of length $$l$$ is joined smoothly with circular track of radius $$R$$. A mass of $$m$$kg is projected up from the bottom of the inclined plane. The minimum speed of the mass to reach the top of the track is given by, $$v=$$

136475.PNG
  • $${ \left[ 2g(l\cos { \theta } +R)(1+\cos { \theta } ) \right] }^{ 1/2 }$$
  • $${ \left( 2gl\sin { \theta } +R \right) }^{ 1/2 }$$
  • $${ \left[ 2g\{ l\sin { \theta } +R(1-\cos { \theta } )\} \right] }^{ 1/2 }$$
  • $${ \left( 2gl\cos { \theta } +R \right) }^{ 1/2 }$$
A particle experiences a net force that is always parallel to y-axis. If it moves along the curve $$xy=a^2$$ where $$a$$ is a constant and the magnitude of the force is $$y^n$$, then $$n$$ is
  • 1
  • 2
  • 3
  • 4
With what speed in miles/hour ($$1 m/s = 2.23 mi/h$$) must an object be thrown to reach a height of $$91.5 m$$ (equivalent to one football field)? Assume negligible air resistance.
  • $$94.4 mi/h$$
  • $$84.4 mi/h$$
  • $$74.4 mi/h$$
  • $$94 mi/h$$
Which of the following statements is correct for a particle travelling with a constant speed?
  • Its position remains constant as time passes.
  • It covers equal distances in unequal time intervals.
  • Its acceleration is zero.
  • It does not change its direction of motion.
A race car accelerates uniformly from $$18.5 m/s$$ to $$46.1 m/s$$ in $$2.47$$ seconds. Determine the distance traveled by the car. (in m)
  • $$79.8 m$$
  • $$79 m$$
  • $$7.8 m$$
  • $$9.8 m$$
An engineer is designing the runway for an airport of the planes that will use the airport, the lowest acceleration rate is likely to be $$3 m/s^2$$. The takeoff speed for this plane will be $$65 m/s$$. Assuming this minimum acceleration, what is the minimum allowed length for the runway? (in m)
  • $$704$$
  • $$70$$
  • $$705$$
  • $$707$$
The driver of a train travelling at $$115\ km\ h^{-1}$$ seen on the same track, $$100\ m$$ in front of him, a slow train travelling in the same direction at $$25\ km\ h^{-1}$$. The least retardation that must be applied to faster train to avoid a collision is
  • $$25\ ms^{-2}$$
  • $$50\ ms^{-2}$$
  • $$75\ ms^{-2}$$
  • $$3.125\ ms^{-2}$$
The graph below shows the distance travelled and the time taken by four cars.
Which car travelled the slowest?
516613_69218fdcf1ac40b381bb56885e71dfc8.png
  • Car $$1$$
  • Car $$2$$
  • Car $$3$$
  • Car $$4$$
A stone is thrown vertically upwards. When the stone is at a height equal to half of its maximum height its speed will be 10 m/s, then the maximum height attained by the stone is (Take g =10 $$m/s^2$$)
  • 3 m
  • 15 m
  • 1 m
  • 10 m
The figure shows the displacement time graph of a particle moving on a straight line path. What is the magnitude of average velocity of the particle over 10 s?
283405_48bd7e939b90400791d6799102f544ff.png
  • $$2\;ms^{-1}$$
  • $$4\;ms^{-1}$$
  • $$6\;ms^{-1}$$
  • $$8\;ms^{-1}$$
A car, moving at 1.5 $$m{s}^{-1}$$ applies brakes and comes to rest in $$2 s$$. If the same car travels at double the speed, what time would it take to come to rest after applying brakes?
  • $$4s$$
  • $$8s$$
  • $$2s$$
  • $$3s$$
The particle is moving with constant speed
986359_1148e5b5985c4139bb7a1e0cc3926855.png
  • In graphs (i) and (iii)
  • In graphs (i) and (iv)
  • In graphs (i) and (ii)
  • In graphs (i)
Two cyclists, k km apart, and starting at the same time, would be together In r hours if they travelled in the same direction, but would pass each other In t hours if they travelled in opposite directions. The ratio of the speed of the faster cyclist to that of the slower is ____
  • $$\frac{r+t}{r-t}$$
  • $$\frac{r}{r-t}$$
  • $$\frac{r+t}{r}$$
  • $$\frac{r}{t}$$
The acceleration will be positive in:
985938_47215d9fd8b9423195a8122ead4b99d7.JPG
  • (I) and (III)
  • (I) and (IV)
  • (II) and (IV)
  • None of these
A spy plane is being tracked by a radar. At $$t=0$$, its position is reported as $$(100 m,\, 200 m, \,1000 m)$$. $$130 s$$ later, its position is reported to be $$(2500 m,\, 1200 m,\, 1000 m)$$. Find a unit vector in the direction of plane velocity and the magnitude of its average velocity.
  • $$20ms^{-1}$$; $$\dfrac{22\hat{i}+5\hat{j}}{13}$$
  • $$20ms^{-1}$$; $$\dfrac{12\hat{i}+5\hat{j}}{13}$$
  • $$30ms^{-1}$$; $$\dfrac{12\hat{i}+5\hat{j}}{13}$$
  • $$20ms^{-1}$$; $$\dfrac{12\hat{i}+6\hat{j}}{13}$$
Speed - distance graph of an object which comes to rest suddenly is
Consider the graph given.
The distance travelled by an object in a given direction as time increases is given by the given graph.
In this context which of the following statements is correct?

931349_d1a00baef63845cf869077de64225d84.png
  • The velocity decreases during DE
  • The velocities during DE and BC are in opposite directions
  • Total distance travelled is AF
  • During CD the body is moving with uniform velocity
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
  • $$200\ m$$
  • $$100\ m$$
  • $$150\ m$$
  • $$250\ m$$
A train is travelling at a speed of $$108\ km/h$$. Brakes are applied so as to produce a uniform retardation of $$1\ m/s^{2}$$. Find how far the train will go before it is brought to rest :
  • $$800\ m$$
  • $$450\ m$$
  • $$1000\ m$$
  • $$1050\ m$$
A jeep starts from rest and attains a speed of $$40\ km\ h^{-1}$$ in $$10$$ minutes. The uniform acceleration will be :
  • $$4\ km\ h^{-2}$$
  • $$4\ km\ s^{-2}$$
  • $$66.7\ m\ s^{-2}$$
  • $$1.85\ cm\ s^{-2}$$
A particle has a velocity u towards east at t =Its acceleration is towards west and is constant, Let $$X_A$$ and $$X_B$$ be the magnitude of displacements in the first 10 seconds and the next 10 seconds. 
  • $$X_A < X_B$$
  • $$X_A = X_B$$
  • $$X_A > X_B$$
  • the information is insufficient to decide the relation of $$X_A$$ and $$X_B$$.
For the graph given below the ratio of average speed to the average velocity in $$( ms^{-1})$$ of the particle is.
1048016_c0da2209434e4a4e96175663375c0ead.png
  • $$\dfrac{5}{6}$$
  • $$\dfrac{5}{8}$$
  • 3
  • 4
Water drops fall at regular intervals from a roof at of $$125\ m$$ from the ground. At an instant when $$11th$$ 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 $$10th$$ drop from the roof is $$(g=10\ m/s^{2})$$
  • $$0.40\ m$$
  • $$0.20\ m$$
  • $$0.80\ m$$
  • $$1.2\ m$$
The splash is heard $$2.05 \ s$$ after the stone is dropped into a well of depth $$19.6 \ m$$. The velocity of sound is?
  • $$342$$ $$ms^{-1}$$
  • $$372$$ $$ms^{-1}$$
  • $$392$$ $$ms^{-1}$$
  • $$352$$ $$ms^{-1}$$
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