1. What is centre of mass?
2. Derive the expression for centre of mass for a system of two particles.
3. What is torque?
4. Write the dimension of torque.
5. Define angular momentum.
6.
7.
8.
9.
10.
Saturday, October 29, 2022
Friday, October 28, 2022
Class 9 sound question bank set-02
2. Why do we hear the sound produced by the humming bees, while the sound of vibration of pendulum is not heard?
3. Write three differences between transverse wave and longitudinal wave.
4. For which property of Sound of same loudness and pitch but produced by different musical instruments like violin and float are distinguishable.
5. State the laws of reflection of sound.
6. A person is listening to a tone of 500 Hz sitting at a distance of 450 m from the source of the sound . What is the time interval between successive compression from the source ? Take speed of sound in air is 330 m/s.
7. A submarine emits a Sonar pulse, which returns from an underwater cliff in 1.02 second. If the speed of sound in saltwater is 1531m/s, how far away is the cliff?
8. What are longitudinal waves? Give two examples.
9. What are transverse wave? Give two examples.
10. What is stethoscope? Name the principle on which stethoscope works.
Solution:
A. Pdf solution.
Set-02 Class 11 Force and laws of motion
1. Can the value of coefficient of friction is more than one.
2. Establishing Newton's third law from Newton's second law of motion.
3. Person is standing on the one end of a plank of mass and length l is floating in water . The person moves from one and to another end and stops. Find the displacement of the plank .
4. Train is moving with the constant acceleration a . A pendulum suspended from the selling of the train. At equilibrium find the angle made by the pendulum with the vertical.
5. A body is kept on a rough horizontal plane. The plane is then gradually rised an inclination 30° the horizontal. At 30° angle the inclination the body will tend to move. When the inclination rises like you more than 30° then the body descent 4 m in 4 second find the coefficient of static friction and kinetic friction between the block and the rough plane.
6. Why it is easier to pulling a cart instead of pushing ?
7. The upper half of an inclined plane with internation 60° is perfectly smooth while the lower house is rough. The body starting from rest at the top we again come to rest at the bottom if the coefficient of friction for the lower half is given by.
8. Action and reaction are equal and opposite why cannot the cancel each other?
9. What is the angular friction between two switches in contact if the coefficient of friction is (1/3) ½?
10. Spring balance is attached to the ceiling of a lift. A man hangs his back on the spring and the spring reads 49 N , when the lift is stationary. What will be the reading of the spring balance if the lift moves downward with an acceleration 5 m/s ²?
Solution comming soon
Thursday, October 27, 2022
Theory question set-01 class-11 Force and laws of motion
1. Write the dimension of coefficient of friction.
2. What do you mean by conservative force?
3. Derive Newton's 1st law from 2nd law.
4. Show that impulse of a force is equal to change in momentum.
5. State the principle of conservation of momentum.
6. Show that momentum before and after an elastic collision is conserved.
7. Establish the principle of conservation of momentum from Newton's 3rd law.
8. State the laws of static friction.
9. When you work on slippery road why we should take small steps.
10. Why does it hurt less when we fall understand that of a hard floor?
Comming soon
Work energy and power class 11 question bank set-01
1. Derive the mathematical relationship between momentum and kinitic energy.
2. What is the dimension of kinitic energy?
3. A body of mass 0.3 kg is taken up an inclined plane to length 10 m height 5 m and then allowed to slide down to the bottom again . The coefficient of friction between the body and the plane is 0.15. What is the
a) work done by the gravitational force over the round trip ,
b) what done by the applied force over the upward journey,
c) what done by the frictional force over the round trip ,
d) kinetic energy of the body at the end of the trip?
4. A body of mass M is moved along a straight line by a machine delivery a constant power P. Find the expression for the distance moved by the body in terms of M ,P and t.
5. Is it necessary that work done in the motion of a body over a closed loop is zero for every force in nature ? Explain.
6. Springs A and B are identical except that A is stiffer than B. In which spring has done more work if they are stressed by same force ?
7. What are conservative forces?
8. Show that the work done in moving a body against the gravity is independent of the path taken. Or , show that gravitational force is a conservative force.
9. A ball bounced to 80% of its original height. What fraction of its mechanical energy is lost in each bounce ? where does this energy go?
10. Write the properties of conservative forces.
Comming soon
Wednesday, October 26, 2022
Work energy and power class 9, question bank set-03
1. List two essential conditions for work to be done.
2. What is the SI unit of work done and power?
3. Find the energy in KWh consumed in 10 hours by a machine of power 500 Watt.
4. Is it possible that some force is acting on a body but still the work done is zero?
5. Derive the expression for potential energy.
6. What is the work done by the force of gravity in the following cases ?
(A) satellite moving around the earth in a circular orbit of radius 3000 km.
(B) stone of mass 250 gram is thrown up through a height of 2.5 m.
7. A person holds a bundle of books over his head for 30 minutes, and get tired . Has he done some work or not? justify your answer.
8. Is it possible that a body be in accelerated motion under the action of a force , yet no work is being done by the force ? Explain with an example.
9. Define one watt power.
10. The kinetic energy of an object of mass m moving with a velocity of 5 m/s is 25 Joule . what will be its kinetic energy when it's velocity is doubled and what will be the mass of this body?
Solution:
A. Pdf solution.
Tuesday, October 25, 2022
Sound class 9 set no 01
1. Name the physical quantity whose SI unit is hertz.
2. If you want to hear a train approaching from far away, why it is more convenient to put the ear into the track ?
3. What is the mathematical relationship between frequently, speed and wave length?
4. What is the SI unit of wave length?
5. If the frequency of a wave is 250Hz , Find time period.
6. Write the full form of SONAR. Which type of sound waves is produced in SONAR?
7. What are the uses of SONAR?
8. What are mechanical waves?
9. On what factor does the pitch of a sound depends?
10. If any explosion takes place at the bottom of a lake, what type of shock wave in the water will take place?
Solution: a) Hand written pdf solution.
Sunday, October 23, 2022
Class - 9 work energy solved series -2
Each question= 2 or 3 marks
1. What happens to the work done when the displacement of a body is at right angles to the direction of force acting on it? Explain your answer.
2. When a ball is thrown inside a bus does its kinetic energy depends on the speed of the bus? Explain.
3. Derive the expression for kinetic energy.
4. State and prove work energy theorem.
5. A body of mass m is moving in a circular path of radius r with constant speed v. Find the work is done by the body after completing one revolution.
6. Work done in the motion of a body over a closed loop is zero for every force in nature, is it true?
7. State and prove law of conservation of energy in case of freely falling body.
8. If the linear momentum of a body is increased by 50% , by what percentage will the kinetic energy be increased?
9. If the kinetic energy of a body is increased by 300% by what percent is will the momentum be increased ?
10. When a Arrow is short from its BOW, it has kinitic energy. From where does it get the kinetic energy?
Solution: See Solution in bengali language
Class ix work energy series -01 Solved
Short Questions
Each question=1 mark
1. How much work is done when a body of mass m is raised to a height h above the ground ?
2. Is energy is a vector quantity?
3. If the speed of a body is halved , what will be the change in its kinetic energy ?
4. What happens to the potential energy of a body when it's height is doubled ?
5. Define 1Kw power.
6. A body does 1200 joule of work in 2 minutes.Calculate it's power.
7. Joule/ second is the unit of which quantity?
8. On what factor does the kinetic energy of a body depends?
9. Find the total work done by a body of 5kg mass moving in a circular path with constant speed of 20m/s for a complete revolution.
10. Find the momentum of a body of mass 100g having a kinetic energy of 20 Joule.
Solution: a) video solution: Solution of question bank set-01 work energy and power class 9
(N.B: video Solution is in Bengali language)
Class x Electric Current questions solved. Series-02
Class x
Electric Current questions solved.
Series-02
Current Electricity
Series-02
One and two Marks questions
1. State Ohm's law.2. Write two limitations of ohms law.
3. How is the voltmeter connected in the circuit to measure the potential difference between two points ?
4. What determines the rate at which energy is delivered by a current ?
5. Why are coils of electric toasters and electric iron's made of an aloy rather than a pure metal ?
6. Why do electricians wear a rubber hand gloves while working with electricity ?
7. A current of 200 mA flows through a 4 kilo ohm registor . What is the potential difference across the registor?
8. How does the resistance of a pure metal changes with temperature ?
9. Write down an expression for the resistance of a metallic wire in terms of resistivity.
10. A wire that has resistance R is cut into two equal pieces. The two parts are joined in parallel . What is the resistance of the combination ?
Solutions: Solved current Electricity question bank set-02
Saturday, October 22, 2022
Class x question answer series-01 (chapter- Electricity)
Question bank for practice:
Chapter: Electric Current
Serial no. 01
Short questions: 1mark each
1. What is unit of electric current?
2. Write the unit of electric potential.
3. The slope of V vs I graph represent the quantity...............
4. Joule/ coulomb is the unit of which quantity ?
5. Are the lights of in your house wired in series?
6. Show how you would connect two 4ohm resistors to produce a combined resistance of 2 ohm?
7. Write the unit of resistivity.
8. How the resistance of a wire vary with its area of cross-section ?
9. How the resistance of a wire vary with its length ?
10. What is the ratio of potential difference and current known as?
Solution: a) video Solution of current Electricity question bank set-01
(N.B : Solution is in Bengali language)
CLASS IX Force and laws of motion SERIES -01 solved
Question bank for practice:
Chapter: Force and laws of motion
Serial no. 01
Short questions: 1mark each
1. What is the SI unit of momentum ?
2. State however momentum is a scalar quantity or a vector quantity .
3. Name the physical quantity whose unit is KG meter/S.
4. Which law law of Newton Newton is known as Galileo's laws of inertia
5. Which quantity is the measure of inertia ?
6. Define 1N force.
7. What is the relationship between force and acceleration?
8. Which physical principal is involved in the working of a jet airplane ?
9. The value of which quantity is zero in case of uniform motion ?
10. Action and reaction always equal and opposite . They acts on ..................... bodies ?
(N.B : solution is in Bengali language)
Wednesday, October 19, 2022
Series-01:Numericals from laws of motion class xi solved for jee neet , mains and advance
1. The pulleys and strings shown in the figure are smooth and of negligible mass. For the system to remain in equilibrium , The angle should be
A. 30° B. 40° C.45° D. 60°
2. A particle moves in the XY plane under the influence of a force such that its linear momentum is p(t)=A[cos(kt) i^ - sin(kt) j^] , where A and k are constants.The angle between the force and momentum is-
A. 0° B. 40° C. 30° D. 90°
Solution: Ans: 90° see Solution
3. What is the maximum value of force such that The block shown in the arrangement does not move
A. 20N B. 10N C. 12N D.15N
4. A string of negligible mass going over a damped pulley of mass m supports a block of mass M shown in the figure. The force on the pulley by the camp is given by-
Solution: Ans See Solution 
5. A block P of mass m is placed on a horizontal frictionless table. A second block Q of same mass m is placed on it and is connected with a spring of spring constant k. Two blocks are pulled by a distance The block Q oscillate with out sleeping.what is the maximum value of frictional force between the two blocks .
A. KA/2 B. KA. C. 0 D. mg×coefficient of friction.
Solution: kA/2 See solution here in Bengali language
6. A train has to negotiate a curve of 400m . By how much should the outer rail be rise with respect to inner rail for a speed of 48 km/h? The distance between the rail is 1m.
A. 0.0045m B.0.045m C.0.45m D.4.5m
7.An electrical bulb Suspended from the roof of a railway train by a flexible wire shifts through an angle of 45° when the train goes horizontally round a curve path of 200m radius , Find the speed of the train.
A. 44.7 m/s B. 90.44m/s C.60.07 m/s D. 75.03 m/s
8.A body of mass M starts sliding down on an inclined plane where the critical angle is 30° as shown in the figure. The Coefficient of kinetic friction will be.....
9. Masses m and M on a pulley move 0.6m in 4 s as shown in the figure. What is the ratio of m/M ?
A. 55/57 B. 49/50 C. 57/55 D. 117/113
10. A body takes t time to reach the bottom of an inclined plane of angle ϴ with the horizontal. If the plane is made rough, time taken now is 2t . The Coefficient of friction of the rough surface is
A. (3/4)tanϴ B. (2/3) tanϴ C.(1/4)tanϴ D. (1/2)tanϴ
Tuesday, October 18, 2022
Physics Numerical
An airplane is flying in horizontal direction with veracity 600 km per hour at height of 1960 m. When it is vertically about the point a on the ground a body is dropped from it the the body strikes the ground at point B point B calculate the distance AB.
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