Q & A

 

Questions and Answers

In this Page we will discuss the Questions and Topics which we cannot discuss in the other pages. Mostly these are the questions asked by the Teacher or Students during our lectures, Explanation of Topics and Derivation of Equations and Formulas.

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We will try to answer these questions in a simple and plain way that can easily be understand by School Level Students.

SSC-I (Class 9)

Q1.       Derive First Equation of motion?

Ans:   Derivation of 1st Equation of motion: Download

Q2.       Derive Second Equation of motion?

Ans:   Derivation of 2nd Equation of motion: Download

Q3.       Derive Third Equation of motion?

Ans:  Derivation of 3rd Equation of motion: Download   

        i.            Q4.    Difference between Circular motion and rotatory motion.

Sr. No.	Circular Motion	Rotatory Motion
1	The motion of an object in a circular path is known as circular motion. For Example: ·           A car moving along a circular track possesses circular motion ·           Motion of the Earth around the Sun ·           Motion of the moon around the Earth.	The spinning motion of a body about its axis is called its rotatory motion. For Example: ·           The motion of a wheel about its axis. ·           The motion of the Earth about its geographic axis. ·           The motion of a top
2	In circular motion, the point about which a body goes around, is outside the body.	In rotatory motion, the line (axis), around which a body moves about, is passing through the body itself.
3

      Q5.    Difference between Distance and Displacement.

Sr. No.	Distance	Displacement
1	Length of a path between two points is called the distance between those points.	Displacement is the shortest distance between two points which has magnitude and direction.
2	Distance is a scalar quantity,	Displacement is a vector quantity.
3	It is denoted by S.	It is denoted by d.

                Q6.    Difference between Speed and velocity.

Sr. No.	Speed	Velocity
1	The distance covered by an object in unit time is called its speed. Speed = Distance covered/Time Taken	The rate of displacement of a body is called its velocity Speed = Displacement/Time Taken.
2	Speed is a scalar quantity,	Velocity is a vector quantity.
3	It is denoted by v.	It is denoted by v.

      Q7.       What are the differences between mass and weight?

Sr. No.	Mass	Weight
1.	Mass of a body is the quantity of matter possessed by the body.	Weight of a body is equal to the force with which earth attracts it.
2.	It is a scalar quantity.	It is a vector quantity.
3.	Its SI unit is kilogram (kg).	Its SI unit is newton (N).
4.	Its value does not change with place.	Its value changes from place to place.
5.	Mass is measured by comparison with standard masses using a beam balance.	Weight is measured with spring balance.

      Q8.       What are the Characteristics of Centripetal Force?

Ans: Following are the characteristics of Centripetal Force

1.    Centripetal force is a force that keeps a body to move in a circle.

2.    Centripetal force is always directed towards the centre and has no component in the direction of motion.

3.    Centripetal Force always acts perpendicular to the motion of the body.  

Q  Q9.    What are the differences between Centripetal Force and Centrifugal Force?

Sr. No.	Centripetal Force	Centrifugal Force
1	The force which keeps the body to move in a circular path is called circular motion.	There exists a reaction to the centripetal force. This centripetal reaction that pulls a body outward is called the centrifugal force.
2	Its direction is towards the centre of the circle. (i.e. from the object towards the centre of the circle)	Its direction is away from the centre of the circle. (i.e. from the centre of circle towards the object)
3	It is a real force.	It is not a real force.
4.	Centripetal force can be caused due to factors like tension, gravitational pull, electrostatic force etc	The inertia of an object causes the centrifugal force.
5.	Example: The motion of moon around the   sun is centripetal force.	Example:  Mud flying off from the tires of a wheel   .

    Q10.    What are the differences between Torque and Couple?

Sr. No.	Torque	Couple
1.	The turning effect of the force is called torque.	A couple is formed by two unlike parallel forces of same magnitude but not acting along the same line.
2.	Torque is produced by a single force.	Couple is formed by two forces.
3.	Torque is the product of force and moment arm L. Torque= Force x Moment arm	Torque Produced by the couple is given by the product of one of the two forces and the perpendicular distance between them.
4.	Examples         i.            Unscrewing a nut using a wrench.       ii.            Open or closing a door by pushing it about its hinges.	Examples         i.            Turning a steering wheel of a car by applying two hands form a couple.       ii.            Turning of a tap is based upon the principle of couple.
5.	In the case of a FREE body (not fixed to a pivot), a torque produces not only rotational motion but also translational motion of the body.	A couple NEVER produces translational motion in a free body.

 Q11.    What are the differences between g and G?

Sr. No.	g	G
1.	‘g’ is gravitational acceleration.	G is the universal constant of gravitation.
2.	‘g’ is the acceleration of freely falling body.	G is a constant of proportionality. Numerically equal to the force of attraction between force of gravitation that between two bodies of unit mass kept at a unit distance apart.
3.	Its value is approximately 10 ms-2 on the surface of earth.	Its value is 6.67x1011 Nm2kg-2.
4.	Its value varies from place to place.	Its value remains same everywhere.
5.	It is a vector quantity.	It is not a vector quantity.

Q12.    What is the difference between Action and Reaction?

Sr. No.	Action	Reaction
1	Action is a cause.	Reaction is an effect due to the cause.
2	Action is the act that you perform on something expecting something to happen,	Reaction is the happening of something which we are expecting in the result of action.
3	Action force acts on one body.	Reaction force acts on another body.
4	Action force acts in one direction	Reaction force acts in other direction
5	The force exerted on an object is the action,	The force experienced by the object due to action as a consequence of Newton's third law is the reaction.

Q13.    What are the differences between Sliding Friction and Rolling Friction?

Sr. #	Sliding Friction	Rolling Friction
1	When an object slides over the surface of another object it is called sliding friction.	When an object rolls over the surface of another object it is called rolling friction.
2	Sliding friction takes place due to interlocking between microscopic surfaces.	Rolling friction takes place due to the deformation of surfaces.
3	The coefficient of sliding friction depends on the texture of the surface and temperature to a certain extent.	The coefficient of rolling friction is dependent on the radius of the rolling object, the depth to which the object can sink, and the toughness of the surface
4	It is greater than rolling friction.	It is lesser than sliding friction.
5	Only a point on the surface remains in contact with the object.	A finite area of the surface remains in contact with the object
6	Sliding friction is given by the relation Fs = µs N	Rolling friction is given by the relation. Fr = µr N

SSC-II (Class 10)

Q1. What are three characteristics of Simple Harmonic Motion?

Ans. Following are the characteristics of Simple Harmonic Motion (SHM)

1. Simple Harmonic Motion is a periodic motion..  
2. In Simple Harmonic Motion the acceleration of a body is directly proportional to its distance from mean position. 
3. In Simple Harmonic Motion the acceleration of a body is always directed towards its mean position.
4. The total energy of the body exhibiting Simple Harmonic Motion is conserved.
5. Simple Harmonic Motion can be represented by a single harmonic function of sine or cosine.  

Q2.: Write down common properties of Longitudinal and Transverse waves?

Following features are similar in longitudinal and transverse waves

1.  Both waves are progressive waves i.e. Both transport energy without transporting matter.
2. Both follow wave equation: v=fλ
3. Both have definite speed, wavelength, frequency, time period and amplitude.
4. Both show reflection, refraction, diffraction, and interference.
5. Particles oscillate about their mean position in both waves.
6. Both have similar sinusoidal graph of displacement against time. 

Q3.:Distinguish between Longitudinal and Transverse waves with suitable examples?

Sr. No.	Longitudinal Waves	Transverse Waves
1	In longitudinal waves the vibratory motion of the particles of the medium is parallel to the direction of propagation of wave.	In transverse waves, the vibratory motion of particles of the medium is perpendicular to the direction of propagation of waves.
2	Longitudinal waves consist on rarefactions and compressions.	Transverse waves consist on crests and troughs.
3	Sound waves. seismic P-waves are examples of longitudinal waves.	Waves on the surface of water, light waves, seismic S waves are examples of transverse waves.
4	Longitudinal waves act in one dimension	Transverse Waves acts in two dimensions.
5	Longitudinal wave cannot be polarized.	Transverse wave can be polarized.
6	Longitudinal waves can be produced in any medium such as gas, liquid or solid.	Transverse waves can be produced in solids and liquid liquids only.

Q4.: Write down any three uses of waves?

1.  Waves transfer energy from one place to another without transferring matter..
2. The sound waves (The ultrasonic waves) are used in examining and curing different diseases.
3. The sound waves (The ultrasonic waves) are used to locate underwater depths or is used for locating objects lying deep on the ocean floor, etc. The technique is called SONAR, (sound navigation and ranging).
4. Radio waves are used for communication such as television and radio.
5. Microwaves are used for cooking food and for satellite communications.

Q5.       What is difference between mechanical waves and electromagnetic waves?

Sr. No.	Mechanical Waves	Electromagnetic waves
1	Waves which require any medium for their propagation are called mechanical waves.	Waves which do not require any medium for their propagation are called electromagnetic waves.
2	Examples of mechanical waves are water waves, sound waves and waves produced on the strings and springs.	Radio waves, television waves, X-rays, heat and light waves etc.
3	Mechanical waves cannot travel through vacuum.	Electromagnetic waves can travel through a vacuum.
4	Mechanical waves are produced due to the vibrations of the particle of the medium.	Electromagnetic waves are produced by the vibration of the charged particles OR .          Electromagnetic waves are formed due to the oscillating electrical and magnetic field.
5	Mechanical waves has speed much lessor than speed of light.	Electromagnetic waves travel at the speed of light.

Q6.       What are the uses of Concave Mirror?

          Uses of Concave Mirrors

1. Concave Mirrors are used as Shaving mirrors or makeup mirrors.
2. In torch, search lights, head lights etc. concave mirrors are used as reflector
3. Concave mirrors are used to focus sunlight to produce heat in the solar furnaces. 

Q7.       What are the uses of Convex Mirror?

          Uses of Convex Mirrors

1. In large shopping centers Convex Mirrors are used for security purpose.
2. Concave mirrors are widely used in automobiles and cars as rare view mirrors and side mirrors.
3. Convex mirrors are used at the sharp turns of the roads for safety purpose.

Q8.       What is difference between Charging by Friction and electrostatic induction?

Sr. #	Charging by friction	Charging by Induction
1.	When two neutral bodies are rubbed against each other, they become electrically charged. This process is called charging by friction.	In the presence of a charged body, an insulated conductor develops positive change at one end and negative charge at the other end. This process is called electrostatic induction.
2	In charging by friction objects are physically in contact with each other.	In charging by induction objects are not in physical contact with each other.
3	In charging by friction charge moves from one body to another body,	In charging by induction no charge flows from charged body to the uncharged body.
4	Some charge is lost in charging by conduction,	There is no loss in any charge in charging by induction.
5	Charging by friction mostly happens in insulators.	Charging by induction mostly happens in conductors,

Q9.       What is difference between Electronic Current and  Conventional Current? 

Sr.  #	Conventional Current	Electronic Current
1	The current flowing from positive to negative terminal of a battery due to the flow of positive charges is called conventional current.	The current flowing from negative to positive terminal of a battery due to the flow of negative charges (electrons) is called electronic current.
2	It has same direction of electric field.	It has opposite direction of electric field.
3	It is the real and actual direction of electric current.	It is assumption or convention used in past for understanding of current.

Q10.       What is difference between Conductors and Insulators? 

Sr. No	Conductors	Insulators
1	Conductors are materials that permit electrons to flow freely from particle to particle.	Insulators are materials that impede the free flow of electrons from atom to atom and molecule to molecule.
2	The conductor allows the electric current to pass through it.	The insulator does not allow the electric current to pass through it.
3	Conductors have Low resistance.	Insulators have very High resistance.
4	Conductors have excess of free electrons.	Insulators have no free electrons.
5	Examples of conductors are silver, copper, aluminium, platinum. Iron etc.	Examples of insulators are glass, wood, plastic, fur, silk etc.

Q11.       How can we differentiate between emf and potential difference?

Sr. No	Electromotive Force (emf)	Potential Difference
1	Electromotive force is the potential difference across the terminals of a battery when it is not driving current in a circuit. i.e. when the circuit is open.	Potential difference is the difference of potentials between any two points in a circuit when current is flowing through it. i.e. when circuit is closed.
2	The electromotive force is the measure of energy that it gives to each coulomb of charge.	The potential difference is the amount of energy used by the one coulomb of charge.
3	It is independent of the resistance of the circuit.	It depends upon the resistance of the circuit.
4	The magnitude of emf has always remained constant	The magnitude of the potential difference varies.
5	The term emf is used only for the source of emf.	It is measured between any two points of the circuit.
6	Emf is the cause.	Potential difference is the effect.
7	The emf is the gains of electrical energy in the circuit.	The potential difference is the loss of electrical energy in the circuit.
8	The magnitude of the electromotive force is always greater than the potential difference when the circuit is uncharged.	When the circuit is fully charged the magnitude of the potential difference is equal to the emf of the circuit.

Q12. What is Difference between Alternating Current (AC) and Direct Current (DC)?

Sr. #	Alternating Current (AC)	Direct Current (DC)
1	The current that changes direction after equal interval of time is called alternating current.	The current that does not changes direction after equal interval of time is called alternating current.
2	It is Bidirectional.	It is unidirectional.
3	Its polarity changes with time.	Its polarity remains constant with time.
4	AC generator is a source of alternating current.	Cell and batteries are sources of direct current.

Q12. Draw Circuit Diagram of NOR gate and NAND gate?

Circuit Diagram of NOR Gate

Circuit Diagram for NAND gate

Q.13: What is Electrical Energy?

Ans: The energy which is caused by the movement of the electrons from one place to another such type of energy is called electrical energy.

or

Electrical energy is the energy derived from electric potential energy or kinetic energy of the charged particles. In general,

HSSC-I/ F.Sc Part I/ 11th Class / 1st Year

Q.1: What is difference between precision and accuracy?

Sr. #	Precision	Accuracy
1	Precision of a measurement is how close the measured values with each other.	Accuracy of a measurement is its closeness to the actual value.
2	Precision depends upon absolute uncertainty in the measurement. i.e., A precise measurement is that which has less absolute uncertainty	Accuracy depends upon the fractional or percentage uncertainty in the measurement. i.ie, a an accurate measurement is that which has less fractional or percentage uncertainty.
3	Precision of a measurement depends upon the position of last significant figure.	The accuracy of a measurement depends upon the number of significant digits.