## Pages

### Conceptual question for Motion in a plane

1. A ball is projected upward at a certain angle with the horizontal .which of the following statement is/are correct. At highest point
a. velocity of the projectile is not zero
b. acceleration of the projectile is zero
c. velocity of the projectile is along the horizontal direction
d. Acceleration of the projectile is vertically upwards

2.which one of the following statement is correct?
a. A body has constant speed but varying velocity
b. A body has constant speed but varying acceleration
c. A body having constant speed cannot have acceleration
d. None of the above

3.which of the following remains constant durng the motion of the projectile fired from a planet
a. KE
b. Momentum
c. Vertical component of the velocity
d. Horizontal component of the velocity

4.what is wrong for a body having uniform circular motion?
a. Speed of the body is constant
b. Acceleration is directed towards the centre
c. Velocity and Acceleration vector are having an angle 45
d. none of the above

5.A body moves along a semicircular track of Radius R.Which of the following statement is true
a. Displacement of the body is 2R
b Distance travelled by the body is πR
c Displacement of the body is πR
d none of the above

6.which of the following is false
a. The speed of the particle at any instant is given by the slope of the displacement-time graph
b. The distance moved by the particle in a time interval from t1 to t2 is given by the area under the velocity -time graph during that time interval
c. Magnitude of the acceleration of the particle at any instant is given by the slope of the velocity time graph
d none of the above

7. A particle is going moving along x-axis.which of the following statement is false
a. At time t1 (dx/dt)t=t1=0,then (d2x/dt2)t=t1=0
b.At time t1 (dx/dt)t=t1 < 0 then the particle is directed towards origin
c.if the velocty is zero for a time interval ,the acceleration is zero at any instant with in the time interval.
d. At time t1 (d2x/dt2)t=t1 < 0 then the particle is directed towards origin

8.A particle starts at time t=0 from x=0 along the positive x-axis with constant speed v .After time t,it return back towards the orgin with the speed 2v and reaches the origin in t/2 sec .Which of the following is true for the whole process
a. Average velocity is zero for the whole process
b Average speed is 4/3v for the whole process
c.Displacment at time t is equal to vt
d. Displacment at time 3t/2 is 2vt

9. The range of the projectile depends upon
a. Angle of the projection
b. Acceleration due to gravity
c. Mass of the projectile
d. The magnitude of the velocity of projection

10. Two bullets A and B are fired horizontally with speed v and 2v respectively.which of the following is true
a. Both will reach the ground in Same time
b. Bullet with speed 2v will cover more horizontal distance on the groud
c.B will reach the ground in less time then A
d. A will reach the ground in less time then B

Solutions

### AIEEE/PMT Test Series (Miscelenious)

Hi all given below are 10 Conceptual Questions you can use to test your knowledge. First solve them all then check them by answers given below.
Question 1.
The dispersion of light in a medium implies that
(a) Lights of different wavelengths travell with different speeds in the medium.
(b) Lights of different frequencies travell with different speeds in the medium.
(c) The refractive index of medium is different for different wavelengths of light.
(d) All of the above

Question 2.
Two waves of intensities I and 4I superpose then maximum and minimum intensities are
(a) 5I, 3I
(b) 9I, I
(c) 9I, 3I
(d) 5I, I

Question 3.
During the X-Ray emission , if the voltage is increased
(a) minimum wavelength decreases
(b) minimum wavelength increases
(c) intensity decreases
(d) intensity increases

Question 4.
The electron in hydrogen atom makes a transition from an excited state to ground state. Which of the following statements is true?
(a) Its Kinetic energy increases and its potential and total energy decreases.
(b) Its Kinetic energy decreases and its potential energy increases and its total energy remains the same.
(c) Its kinetic and total energy decreases and its potential energy increases.
(d) Its kinetic, potential and total energy decreases.

Question 5.
The magnitude of emf across the secondary coil of transformer depends on
(a) the magnitude of emf applied across the primary
(b) the number of turns in the primary
(c) the enumber of turns in the secondary
(d) The resistance of primary and secondary

Question 6.
A constant voltage is applied between the two ends of uniform metallic wire. Some heat is developed in it. The heat developed is doubled if
(a) both the lengtha and radius of wire are halved
(b) both the length and radius of wire are doubled
(c) the radius of the wire is doubled
(d) the length of wire is doubled

Question 7.
A. Frictional forces are conservative forces
B. Potential energy can be associated with frictional forces
(a) A and B both are true and B is correct explaination of A
(b) A and B are true but B is not a correct explaination of A
(c) A is wrong and B is correct
(d) both A and B are wrong

Question 8.
A solid sphere and a hollow sphere of same material and size are heated to the same temperature and allowed to be cooled in the same surroundings. If the temperature difference between the surroundings and each sphere is T, then
(a) The hollow sphere will cool at a faster rate for all values of T.
(b) The solid sphere will cool at faster rate for all values of T
(c) both spheres will cool at same rate for all values of T.
(d) both sphere will cool at the same rate only for small values of T.

Question 9.
The moment of inertia of semicircular disc of mass M and radius R about a line perpandicular to the plane of the disc and passing through its centre is
(a) MR2/2
(b) 3MR2/2
(c) 5MR2/4
(d) MR2

Question 10.
A uniform wire of cross-sectional area A and Young's modulus Y is stretched within the elastic limits. If S is the stress in the wire then the elastic energy density stored in the wire in terms of given parameter is
(a) S/2Y
(b) 2Y/S2
(c) S2/2Y
(d) S2/Y

All the very best for your competitive exams.
Physics Expert

Solutions
1. (d)
2. (b)
3. (a)
4. (a)
5. (a), (b), (c)
6. (b)
7. (d)
8. (c)
9. (a)
10. (c)

### Thermodynamics Questions along with solutions (Questions for IITJEE)

Question 1:A gas is contained in a vertical, frictionless piston cylinder device. The piston has a mass of 20 kg with a cross-sectional area of 20 cm2 and is pulled with a force of 100N. If the atmospheric pressure is 100 kPa, determine the pressure inside.

Question 2:A piston-cylinder device has a ring to limit the expansion stroke. Initially the mass of Oxygen is 2 kg at 500 kPa, 30° C. Heat is now transferred until the piston touches the stop, at which point the volume is twice the original volume. More heat is transferred until the pressure inside also doubles. Determine the amount of heat transfer and the final temperature.

Question 3: A piston cylinder device contains 1 kg of oxygen at 150 kPa, 30°C. The cross-sectional area of the piston is 0.1 m2. Heat is now added causing gas to expand. When the volume reaches 0.2 m3, the piston reaches a linear spring with a spring constant of 120 kN/m. More heat is added until the piston rises another 25 cm. Determine the final pressure, temperature and the energy transfers.

Question 4:Is the energy of the system U an intensive or extensive variable?

Question 5:Suppose we have M+N systems prepared, and the first is in thermal equilibrium with the second, the second in thermal equilibrium with the third, etc., until system M+N- 1 is in thermal equilibrium with the M+Nth system. Is the first system in thermal equilibrium with the M+Nth?

Question 6:A gas is contained in a cylinder with a moveable piston on which a heavy block is placed. Suppose the region outside the chamber is evacuated and the total mass of the block and the movable piston is 102 kg. When 2140 J of heat flows into the gas, the internal energy of the gas increases by 1580 J. What is the distance s through which the piston rises?

Question 7:A resistance thermometer is such that resistance varies with temperature as
RT=R0(1+aT+bT5)
where T represent Temperature on Celsius scale And a,b,R0 are constants.R0 unit is ohm
Based on above data ,Find out the unit of a,b

Solutions

Please take a look at other Thermal post
Thermal Expansion
Study Tips Part 1
Study Tips Part 2
Thermo Quick Recap
Conceptual Questions Part 1
Conceptual Questions Part 2
Conceptual Questions Part 3
Conceptual Questions Part 4
IITJEE Objective Questions part 1
IITJEE Objective Questions Part 2
Thermal Expansion Problems
IITJEE Subjective Questions
Thermo Questions

### Second derivatives of vector fields and product rules

There are number of rules that we might use while solving problems involving vector differentiation. These are

1.Sum rule

2. Multiplication by a constant

3. Product rule

fig3

4. Quotient rule

fig4

5.

### Semiconductor Physics (Things you should know)

1. Resistance of a pure semiconductor is millions and millions of times greater then that of a good conductor like copper.
2 Charge carriers in semiconductors are electrons(-e) and holes(p having charge equal to +e).
3 Pure semiconductor known as intrinsic semiconductor contains equal number of both holes and electrons.
4 Drift velocity of electrons is greater then that of holes.
5 Taking both charge carriers in semiconductor into account current is given as I=neA(vn+vp) where n is number of holes and electrons, vn is the drift velocity of electrons and vp is drift velocity of holes and A is the cross-sectional area.
6 Electrical resistance of pure semiconducter decreases with increase in temperature.
7 Semiconductors can be doped with a tiny amount of impurity such as one part in a million to form an impure or extrinsic semiconductor.
8 p-type semiconductor is a type of ectrinsic semiconductor formed when pure semiconductor is doped with trivalent element (for ex- indium). It has large majority of holes and small minority of electrons. Thus majority charge carriers in a p-type semiconductor are holes.
9 n-type semiconductor is a type of ectrinsic semiconductor formed when pure semiconductor is doped with pentavalent element (for ex- phosphorus). It has large majority of electrons and small minority of holes. Thus majority charge carriers in a p-type semiconductor are electrons.
10 Junction diode is a simplest kind of semiconductor device. It has a pn junction and consists of a p-type crystal and n-type crystal and is formed by growing n-type semiconductor over p-type semiconductor. Junction diodes are used as rectifiers.
11 Bipolar junction transistor is a three terminal device. There are two type of transistors npn and pnp transistor. Three terminals of the transistor are joined to base, emitter and collector of the transistor.
12 With Common emitter transistor, the base current Ib is the input current and the

### Gravitation questions for IITJEE

1.Which is of the following statement is true
A) Gravitational constant G value does not depend on the medium between the bodies
B) Gravitational constant G depends on the masses of the bodies and the sizes of the bodies
a A & B both are correct
b only A is correct
c Only B is correcr
d A and B both are wrong

2.If the distance between the earth and sun were half its present value,the number of days in a year would be
a. 64.5
b. 129
c. 182.5
d. 730

3.if both the mass of earth and its radius are decreased by 1%,the value of acceleration of gravity will
a. Decrease by 1%
b Increase by 1%
c. Increase by 2%
d remain unchanged

4. A body weigh W newton of the surface of the earth.Its weight at a height equal to half the radius of the earth will be
a. W/2
b. 2W/3
c. 4W/9
d. W/4

5.when a stone of mass m is falling in th earth of mass M,the acceleration of the earth will be
a zero
b. mg/M
c. Mg/m
d g

6.The weight of the object will be
a. zero at the center of the earth
b.same in all the satellites
c. same at all the points on the surface of the earth
d. none of the above

7.Which is of the following statement is true
A) it is possible to put an artificial satellite in a orbit such a way that it will remain always directly over New Delhi
B) An earth satellite continues to move in the orbit due to centripetal force provided by the burning of the fuel of its engine
a A & B both are correct
b only A is correct
c Only B is correcr
d A and B both are wrong

8. A mass m is divided into two part ym and (1-y)m .For a given seperation,the value of y for which the gravitattional attraction between the two pieces becomes maximum
a. 1/2
b. 3/5
c. 1
d 2

9.Two bodies of mass M and 2M are at rest at infinte seperation.They move towards each other under the mutual gravitaional attraction.Then at seperation r ,which of the following is false
a. The total energy of the system is not zero
b The force between them is zero
c. The center of the mass of the system is movind
d non of the above

10.Choose the correct statement
a. the gravitational forces between the two bodies are an action and reaction pair
b. G and g are constant everywhere
c.The acceleration due to gravity increase due to rotation of the earth
d. none of the above

Solutions

### String, pully and spring

A lot of problems in mechanics involves string, pulley and springs for example masses are attached to string or spring and so on. Here are some concepts you need to remember while solving problems involving string, spring and pulleys.
(1) String
A. If not staded in the question consider the string to be inextensible.
B. Different blocks connected to an inextensible string would have same acceleration and for extensible string blocks would have different acceleration until the string can stretch.
C. Unless otherwise specified consider the string to be light i.e., consider its mass to be negligible in comparison to the block connected to it.
D. For a massless string tension in the string is zero although an ideal massless string is an practical impossibility.
E. Tension on different parts of the string would be different if string possess a considerable mass.

(2) Pulley
A. Unless or otherwise specified consider the pulley to be light having no effect on the system due to its weight.
B. The tension on strion on either side of pulley is taken to be same
C. If not specified consider the oulley to be frictionless in nature.

(3) Spring
A. Unless or otherwise specified consider the spring to be light and force constant of spring is same throughout whole length of the spring.
B. Spring has a elastic property that it can be compressed and stretched easily.
C. To stretch or compress a spring equal and opposite forces have to be applied at both the ends of the spring and in responce spring apply equal and opposite restoring force to bring the spring back to its natural position.
D For small compression and elongations this restoring force is given by Hook's Law which is
F=kx
where k is the spring constant and x is elongation or compression from the natural length of the spring.

So keep solving more and more physics problems Keeping these facts in mind. All the very best for your exams.

### IITJEE Tips and Tricks

Solve Force and motion problems easily
(1) First read the problem carefully.
(2) Determine which type of force is exerted in the system and where it is exertwd.
(3) See whether Newton's law of motion are applicable for the particular system or not i.e., see wherher frame of referance you are working with is inertial or non-inertial frame of refrence.
(4) Determine the system of units you have to use to solve a problem. If physical quantities in the question are given in different units then convert them to a convinent unit you want to work with generally S.I. system of unit is used in our text books.
(5) See if frictional forces are acting on the system if yes then take them into account.
(6) While taking care of friction forces see if they are static or kinetic in nature and accordingly work with them.
(6) Look for the direction of the frictional forces.
So keeping these simple points in mind you can solve force and motion problems easily

### Physics pocket diary of concepts and formulas

A good news for you physicscatalyst.com has made available physics pocket diary of concepts and formulas. This small E-Book contains concepts and formulas of all plus two level physics you need to have in that last hour before going to examination hall.

So what are you waiting for visit the linnk given below and download your own free copy of Physics pocket diary of concepts and formulas.