Mechanics
Mechanics
Mechanics
7-A body of mass ‘m’ moving with velocity ‘u’ collides with a stationary body of mass ‘2m’ and coalesce
to form one body. The speed of the system after collision, is
a. 3u
b. u/3
c. 2u
d. u/4
(Ans: b)
8-For an object moving in uniform circular motion with constant speed. The direction of The
instantaneous acceleration vector is
a. tangent to the path of motion
b. equal to zero
c. directed radially outward
d. directed radially, inward
(Ans: d)
9-The acceleration due to gravity on the moon is 1.6 meters per Second Square. On the moon, the time
period of a pendulum whose length is 6.4 meters will be
a. π seconds
b. 2π seconds
c. 4π seconds
d. 8π seconds
(Ans: c)
11-The velocity of a body depends on time as v=20 +0.1t 2. The body is undergoing
a. uniform acceleration
b. uniform retardation
c. non-uniform acceleration
d. non-uniform retardation
(Ans: c)
14-A person moves 3m towards East and then 4m towards North. The resultant displacement from the
initial position to final position is
a. 7m
b. 5m
c. 4m
d. 1m
(Ans: b)
15-A student goes from his house to school on his bicycle. The distance traveled by him is given by the
relation x: (4t+6t2+3), where distance x is in meters and time t is in seconds. The acceleration of his bicycle
after 30 seconds is
a. 360m/s2
b. 120m/s2
c. 36m/s2
d. 12m/s2
(Ans: d)
18- A particle of mass ‘m0’ moves with speed 0.8c, where ‘c’ is the speed of light in vacuum. The
relativistic kinetic energy of the particle is nearly
a. 1.66m0c2
b. m0c2
c. 0.32m0c2
d. 0.66 m0c2
(Ans: d)
20-A motor cyclist moving with a velocity of 72km/hr on a flat road takes a turn at a point where the
radius of curvature of the rod is 20m(g=10m/s2).In order to avoid sliding, he must not bend with respect
to the vertical by an angle 0 greater than
a. tan-1 2
b. tan-1 4
c. tan-1 6
d. tan-1 25.92
(Ans: b)
21-A particle of mass 0.5 kg is moving in a circle of radius 0.1 m with a constant speed of 2.0m/s. Its
acceleration at any moment is
a. zero
b. 10 m/s2
c. 25 m/s2
d. 40 m/s2
(Ans: d)
22-lf the kinetic energy of a body becomes four times its initial value, the new momentum will be
a. Three times the initial value
b. Four times the initial value
c. Two times the initial value
d. unchanged
(Ans: c)
23-A ship of mass 3x 10^7 kg initially at rest, can be pulled through a distance of 3m by means of force 5x
10^4 N. The water resistance is negligible. The speed attained by the ship is
a. 0.1m/s
b. 0.5m/s
c. 1.0m/s
d. 5.0m/s
(Ans: a)
24-If the radius of the earth were to shrink, its mass remaining the same, the value of acceleration due to
gravity at the pole and at the equator will
a. Increase and decrease respectively
b. Decrease and increase respectively
c. Increase at both places
d. Decrease at both places
(Ans: c)
26-A particle is dropped from a point above the earth. The ratio of the distance travelled in the first two
seconds and in the next two seconds is
a. 1:1
b. 1:2
c. 1:3
d. 1:4
(Ans: c)
27-A mass ‘M’ when attached to the lower end of a mass less spring, whose upper end is fixed, extends it
by ‘L’. In the extended equilibrium state of the spring, the restoring force exerted by the spring on the
mass is
a. Mg
b. Mg/2
c. 2/Mg
d. Zero
(Ans: a)
28-Under the influence of a transverse magnetic field, an electron moves in a circle with constant speed
‘v’. The time period of revolution is
a. Proportional to v
b. Proportional to v2
c. Proportional to √v
d. Independent of v
(Ans: d)
29-The maximum velocity of a particle, executing simple harmonic motion with amplitude 7 mm, is 4.4
m/s. The period of oscillation is
a. 100.00 s
b. 10.00 s
c. 0.10 s
d. 0.01 s
(Ans: d)
31-Relative to its period on the earth, the period a pendulum on the moon is
a. Shorter
b. Longer
c. The same as on the earth
d. Varies with time
(Ans: b)
34-The speed of sound in air is ‘v’, the fundamental frequency of the air column in a pipe of length ‘L’
closed at one end is
a. v/4L
b. v/2L
c. 3v/4L
d. v/L
(Ans: a)
Q.35.A particle executes S.H.M of amplitude a. Its kinetic energy is equal to potential energy u then the
displacement of the particle from the mean position is
a. 0.512a
b. 0.709a
c. 0.827a
d. 0.983a
(Ans: b)
36-Ultrasonic waves are used in SONAR with greater advantage because ultrasonic’s
a. Have low frequency
b. Have short wavelength
c. Are electromagnetic waves
d. Can be easily produced
(Ans: b)
37-The equation of a S.H.M is y=8 sin (2x-40t), where the distances and time are in centimeter and second
respectively. The speed of the wave is
b. 2.0cm/sec
c. 20cm/sec
d. 30cm/sec
e. 40cm/sec
(Ans: b)
38-The velocity of sound in air is 330m/s. The velocity of an observer who observes drop of 10% in the
sound from a stationary source is
a. 30 m/s
b. 33 m/s
c. 297 m/s
d. 330 m/s
(Ans: b)
39-The displacement y of a particle as a function of time t is given by y= e^iαt, where α is a constant and
i= √-1. From amongst the following, the correct statement is
a. The motion is not simple harmonic motion
b. The motion is simple harmonic motion only if ‘α’ is positive
c. the motion is simple harmonic motion only if ‘α’ is negative
d. The motion is simple harmonic motion for all values of ‘α’
(Ans: d)
40-Spherical aberration in a thin lens can be reduced by
a. Using monochromatic light
b. Using a doublet combination
c. Using a circular annular mask over the lens
d. Increasing the size of the lens
(Ans: c)
41-The displacement equation of a wave propagating in a medium is y=a sin k(x-αt), where y is the
particle in the medium at a distance x at any instant t. The correct statement is
a. The velocity of the wave is α.
b. The wave is advancing in the negative direction of the x-axis.
c. The wavelength is k/2π.
d. The frequency of the wave is α.
(Ans: a)
42-The speed of a wave is 360 m/s and the frequency is 5 hertz. The phase difference between two points
is 600. The path difference between them will be
a. 0.72 m
b. 1.20m
c. 12.00 m
d. 120.00 m
(Ans: c)
43-The ratio of intensities of two waves is 1:9. If these waves produce interference, the ratio of maximum
to the minimum intensities will be
a. 1:4
b. 4:1
c. 1:3
d. 3:1
(Ans: b)
44-A thin transparent plate of Polaroid is placed on another similar plate such that the angle between
their pass axes is 30 degree .The ratio of intensities of emergent and unpolarised incident light will be
a. 1:4
b. 1:3
c. 3:4
d. 3:8
(Ans: c)
45-The velocity of light emitted from a source S as measured by a stationary observer O is c. If the
observer moves with a velocity v towards S, then velocity of light as seen by him will be
a. c+v
b. c-v
c. c
d. v/c
(Ans: c)
46-The concept that each point on a wave front may be considered as a new wave source is given by
a. Snell’s Law
b. Huygen’s principle
c. young’s Law
d. Hertz’s Law
(Ans: b)
47-A light ray of wavelength -5895 A0 travelling in vacuum enters a medium of refractive index 1.5. The
wavelength of the ray in the medium is
a. 3930 A0
b. 4200 A0
c. 5495 A0
d. 7893 A0
(Ans: a)
48-A point object is placed at the focus A of a double concave lens of focal length f. Its image will be
formed at a point
a. Between the point A and the lens
b. At a distance between f and 2f from the lens
c. At a distance more than 2f from the lens
d. Infinity
(Ans: a)
49-The resolving Power of a plane transmission grating (having 15000 rulings on the grating surface) in
the second order is
a. 15,000
b. 30,000
c. 45,000
d. 60,000
(Ans: b)