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The basic types of forces in the Universe are:
(i) Gravitational force
(ii) Electro-magnetic force
(iii) Nuclear force, and
(iv) Weak force.
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Two advancements in technology on the basis of Physics are:
(i) The study of satellites has made it possible to forecast the weather.
(ii) The study of electro-magnetic induction has led to design the electric generators and motors.
The familiar branches of science and their fields of study are:
(i) Chemistry: It is the branch of science which deals with the study of occurrence and structure of matter and interaction of various kinds of matter with each other.
(ii) Botany: It is the branch of science, which deals with the study of plants.
(iii) Zoology: It is the branch of science which deals with the study of animal life.
(iv) Geology: It is the branch of science which deals with the study of the earth.
(v) Physics: It is that branch of science that deals with the study of interaction between matter and energy.
Unification of terrestrial and celestial mechanics means same law of motion and law of gravitation are applicable to the motion of heavenly bodies and bodies on the surface of the earth.
Isaac Newton discovered the unification of terrestrial and celestial mechanics, which is called Universal Gravitation today.
Science, like any knowledge, can be put to good or bad use, depending on the user.
Given below are some of the applications of science.
Formulate your views on whether the particular application is good, bad or something that cannot be so clearly categorized:
(a) Mass vaccination against small pox to curb and finally eradicate this disease from the population. (This has already been successfully done in India).
(b) Television for eradication of illiteracy and for mass communication of news and ideas.
(c) Prenatal sex determination.
(d) Computers for increase in work efficiency.
(e) Putting artificial satellites into orbits around the Earth.
(f) Development of nuclear weapons.
(g) Development of new and powerful techniques of chemical and biological war-fare.
(h)Purification of water for drinking.
(i) Plastic surgery.
(j) Cloning
(a) Good
(b) Good
(c) Bad
(d) Good
(e) Good
(f) Bad
(g) Good
(h) Good
(i) In some cases good and in some cases bad.
(j) Cannot be clearly categorized
Some well known branches of Physics are:
(i) Mechanics
(ii) Heat and thermodynamics
(iii) Light
(iv) Sound
(v) Electricity and Magnetism
(vi) Nuclear Physics
(vii) Electronics
(viii) Solid State Physics
(ix) Particle Physics
(x) Astronomy.
Though the law gives women equal status in India, many people hold unscientific views on a woman's innate nature, capacity and intelligence, and in practice give them a secondary status and role. Demolish this view using scientific arguments, and by quoting examples of great women in science and other spheres; and persuade yourself and others that, given equal opportunity, women are on par with men.
Which one of the following bonds produces a solid that reflects light in the visible region and whose electrical conductivity decreases with temperature and hs high melting point?
metallic bonding
van der Waal's bonding
Ionic bonding
covalent bonding
A.
metallic bonding
Metallic bonding is formed due to the attraction of valence (free) electrons with the positive ion cores. Their conductivity decreases with rising of temperature. When visible light falls on a metallic crystal, the electrons of atoms absorb visible light, so they are opaque to visible light. However, some orbital electrons absorb energy and reach to an excited state. They then return to their normal state, remitting light of the same frequency.
If the lattice parameter for a crystalline structure is 3.6 A, then atomic radius in fcc crystal is
1.18 A
2.10 A
2.92 A
1.27 A
D.
1.27 A
Atomic radius is the distance between two nearest neighbours. For Fcc crystal 
The angle through which a cyclist bends when he covers a circular path of 34.3 m circumference in sec is (g=9.8 m/s)
150
300
600
450
D.
450
.Given:-Speed of particle V==
radius r==
tan===
tan = 1 .....(tan450=1)
The radius of earth is 6400 km and g = 10 m/s2. In order that a body of 5 kg weight is zero at the equator, the angular speed is
A.
Given:- radius of earth=6400km=6400103, g=10m/s2
g'=0, m=0(weight is Zero at equator)
g=R2 2=
Angular speed===
The escape velocity for the earth is 11.2 km/sec. The mass of another planet 100 times mass of earth and its radius is 4 times radius of the earth. The escape velocity for the planet is
56.0 km/sec
280 km/sec
112 km/sec
56 km/sec
A.
56.0 km/sec
Escape velocity of earth Ve=11.2km/sec
vescape=
Hence,
Or
Vp= 5Ve=511.2 =56km/sec
A wheel rotates with constant acceleration of 2.0 radian/sec2 .If the wheel starts from rest the number of revolution it makes in the first ten second, will be approximately
32
24
16
8
C.
16
Angular acceleration= 2 rad/s2
Time interval t= 10sec
Angular displacement θ = ?
Dimension of relative density is
kgm-3
ML-3
dimensionless
M2L-6
C.
dimensionless
Relative density is ratio of densities of two substances, so it is dimensionless
A ball is thrown from height 'h' and another from '2h'. The ratio of time taken by the two balls to reach ground is
2:1
1:2
A.
For the first ball,
A ball is thrown upwards, it takes 4sec to reach back to the ground. Find its initial velocity
30ms-1
10ms-1
40ms-1
20ms-1
D.
20ms-1
Since the ball is thrown upwards and it reaches back, so time to reach maximum height is half of the total time i.e
tmaximum = 2sec
Also speed at maximum height is zero, so
If force
10units
units
20units
A.
10units
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A body is moving in a circular path with acceleration 'a'. If its velocity gets doubled, find the ratio of acceleration after and before the change
1:4
2:1
4:1
A.
1:4
D.
4:1
In a circular motion
Acceleration due to gravity at earth's surface is 'g'ms-2 . Find the effective value of gravity at a height of 32 km from sea level (Re=6400km)
0.5 gms-2
0.99 gms-2
1.01 gms-2
0.90 gms-2
B.
0.99 gms-2
For height 'h' above the earth's surface
Near earth's surface, time period of a satelliteis 4 hrs. Find its time period at height '4R' from the centre of earth
32 hrs
8hrs
16hrs
A.
32 hrs
We know
T2∝ R3
A particle of mass m moving with velocity v collides with a stationary particle of mass 2m. The speed of the system, will be
3v
2v
C.
According to conservation of momentum
change in moment is eual to final momentum
m1v1+m2v2= (m1+m2)v'
mv+2m×0= (m+2m)v'
so, v'=
A stone is thrown with an initial speed of 4.9m/s from a bridge in vertically upward direction.It falls down in water after 2sec. The height of bridge is
24.7m
19.8 m
9.8 m
4.9 m
C.
9.8 m
Here :- Initial velocity u=-4.9m/s (-ve is due to vertically upward motion)
Total time t = 2sec
The height of the bridge is given by
s =ut+
Here we consider a=gacceleration due to gravity
A ball of mass 10 g moving with acceleration of 20 m/s2 is hit by a force which acts on it for 0.1 sec. The impulsive force is
1.2Ns
0.3Ns
0.1Ns
0.5Ns
B.
0.3Ns
Here:- Mass of the ball m= 10 g ; time dt =0.1 sec ;
acceleration of the ball = 20m/s2
Force F =ma =0.15×20 =3N
Impulsive forces are forces that act over short times producing rapid changes in motion
Impulsive force = F×dt = 3×0.1 =0.3 Ns
The earth of mass =6×1024 kg revolves around the sun with an angular velocity of 2×10-7 rad/s in a circular orbit of radius 1.5×108 km. The force exerted by the sun on earth is
6×1019 N
18×1025 N
36×1021 N
27×1039 N
C.
36×1021 N
Here :- Mass of earth Me =6×1024 kg
Angular velocity of earth ω =2×10-7 rad/sec
Radius of circular orbit R =1.5×108 km
=1.5×1011m
Force exerted on earth by the sun is given by
F= MeRω2
=6×1024×1.5×1011×(2×10-7)2
=3.6×1022
=36×1021 N
The work done in pulling up a block of wood weighing 2 kN for a length of 10 m on a smooth plane inclined at an angle of 15° with the horizontal is
9.82 kJ
89 kJ
4.35 kJ
5.17 kJ
D.
5.17 kJ
Here :- Weight of block;ω = 2kN; Distance d =10m
Angle of inclination on the plane α =150
The block will be pulled up on a smooth plane
Hence,force of resistance due to the inclination
F =ωsinα = 2×103×Sin 150
=2×103×0.2588
=0.5176 kN
Now work done W = force×displacement =0.1576×103×10=5.17kJ
If the heat of 110 J is added to a gaseous system, whose internal energy is 40 J, then the amount of external work done is
180J
70J
110J
30J
B.
70J
Heat added to the system ΔQ =110J
Internal energy Δu =40J
External work done is given by
ΔW= ΔQ-Δu=110-40=70J
The ratio of electrostatic and gravitational forces acting between electron and proton separated by a distance 5×1011m will be (charge on electron =1.6×10-19 C, mass of electron =9.1×10-31 kg, mass of proton =1.6×10-27 kg, G=6.7×10-11 Nm2/kg2 )
2.36×1039
2.36×1040
2.36×1041
2.34×1042
A.
2.36×1039
Gravitational force is the force of mutual attraction between any two objects by virtue of their masses
Coulomb force also called electrostatic force or coulomb interaction, attraction or repulsion of particles or objects because of their electric force.
Amount of work which can be obtained from 200 cal heat, will be
280 J
800 J
420 J
840 J
D.
840 J
Amount of work done is given by
W=200cal= 200×4.2 J= 840 J (1 cal=4.2J)
The spring extends by x on loading, then energy stored by the spring is (if T is the tension in spring and k is
spring constant
A.
The spring force is an example of variable force which is conservative.
Assertion: Unlike electric force and gravitational forces, nuclear force has limited range.
Reason: Nuclear force do not obey inverse square law.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
B.
If both assertion and reason are true but reason is not the correct explanation of assertion.
Gravitational force:- Weakest force, but infinite range ( not part of standard model)
Weak Nuclear Force:- Next weakest, but short range
Electromagnetic Force:- Stronger, with infinite range
Strong Nuclear force:- strongest, but short range
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