ch 8 important qesction
Motion
Multiple Choice Questions
1.
A
particle is moving in a circular path of radius r. The displacement after half
a circle would be:
(a)
Zero
(b)
p
r
(c)
2
r
(d)
2p
r
2.
A
body is thrown vertically upward with velocity u, the greatest height h to
which it will rise is,
(a)
u/g
(b)
u2/2g
(c)
u2/g
(d)
u/2g
3.
The
numerical ratio of displacement to distance for a moving object is
(a)
always
less than 1
(b)
always
equal to 1
(c)
always
more than 1
(d)
equal
or less than 1
4.
If
the displacement of an object is proportional to square of time, then the
object moves with
(a)
uniform
velocity
(b)
uniform
acceleration
(c)
increasing
acceleration
(d)
decreasing
acceleration
5.
From
the given v – t graph (Fig. 8.1), it can be inferred that the object is
(a)
in
uniform motion
(b)
at
rest
(c)
in
non-uniform motion
(d)
moving
with uniform acceleration
6.
Suppose
a boy is enjoying a ride on a merry-go-round which is moving with a constant speed
of 10 m s–1. It implies that the boy is
(a)
at
rest
(b)
moving
with no acceleration
(c)
in
accelerated motion
(d)
moving
with uniform velocity
7.
Area
under a v – t graph represents a physical quantity which has the unit
(a)
m2
(b)
m
(c)
m3
(d)
m
s-1
8.
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
9.
Which
of the following figures (Fig. 8.3) represents uniform motion of a moving
object correctly?
10.
Slope
of a velocity – time graph gives
(a)
the
distance
(b)
the
displacement
(c)
the
acceleration
(d)
the
speed
11.
In
which of the following cases of motions, the distance moved and the magnitude
of displacement are equal?
(a)
If
the car is moving on straight road
(b)
If
the car is moving in circular path
(c)
The
pendulum is moving to and fro
(d)
The
earth is revolving around the Sun
Short Answer Type
Questions
12.
The
displacement of a moving object in a given interval of time is zero. Would the
distance travelled by the object also be zero? Justify you answer.
13.
How
will the equations of motion for an object moving with a uniform velocity
change?
14.
A
girl walks along a straight path to drop a letter in the letterbox and comes
back to her initial position. Her displacement–time graph is shown in Fig.8.4.
Plot a velocity–time graph for the same.
15.
A
car starts from rest and moves along the x-axis with constant acceleration 5 m
s–2 for 8 seconds. If it then continues with constant velocity,
what distance will the car cover in 12 seconds since it started from the rest?
16.
A
motorcyclist drives from A to B with a uniform speed of 30 km h–1 and
returns back with a speed of 20 km h–1. Find its average speed.
17.
The
velocity-time graph (Fig. 8.5) shows the motion of a cyclist. Find (i) its
acceleration (ii) its velocity and (iii) the distance covered by the cyclist in
15 seconds.
18.
Draw
a velocity versus time graph of a stone thrown vertically upwards and then
coming downwards after attaining the maximum height.
Long Answer Type Questions
19.
An
object is dropped from rest at a height of 150 m and simultaneously another
object is dropped from rest at a height 100 m. What is the difference in their
heights after 2 s if both the objects drop with same accelerations? How does
the difference in heights vary with time?
20.
An
object starting from rest travels 20 m in first 2 s and 160 m in next 4 s. What
will be the velocity after 7 s from the start.
21.
Using
following data, draw time – displacement graph for a moving object:
Use this graph to find average velocity for first 4 s, for next 4 s and for last 6 s.
Use this graph to find average velocity for first 4 s, for next 4 s and for last 6 s.
22.
An
electron moving with a velocity of 5 × 104 m s-1 enters into a
uniform electric field and acquires a uniform acceleration of 104 m s-2 in
the direction of its initial motion.
(i)
Calculate
the time in which the electron would acquire a velocity double of its initial
velocity.
(ii)
How
much distance the electron would cover in this time?
23.
Obtain
a relation for the distance travelled by an object
moving with a uniform acceleration in the interval between 4th and
5th seconds.
24.
Two
stones are thrown vertically upwards simultaneously with their initial
velocities u1 and u2 respectively. Prove that
the heights reached by them would be in the ratio of u21 :
u22 ( Assume upward acceleration is –g and downward
acceleration to be +g ).
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