Junior Inter Physics Important Questions 2 Marks Questions Chapter - I [Physical world] Chapter - 2 [Units and Measurements]

Transcription

1 Junior Inter Physics Important Questions 2 Marks Questions Chapter - I [Physical world] 1. What is the discovery of C.V.Raman? 2. Which of the following has symmetry. a) Acceleration due to gravity. b) Law of gravitation. Chapter - 2 [Units and Measurements] 1. Distinguish between accuracy and precision. 2. How can systematic errors can be minimised or eliminated? 3. What are significant figures and what do they represent when reporting the result of a measurement? 4. Distinguish between fundamental and derived units 5. Why do we have different units for same physical quantities. 6. Express unified atomic mass unit in kg. 7. In a system of units, the unit of force is 100 N. unit of length is 10 m and unit of time is 100 S. What is the unit of mass in this system. 8. State the no. of significant figures in the following a) 6729 b) c) d) e) The error in the measurement of radius of a sphere is 1%. What is the error in the measurement of volume. A 4 B 1 /3 10. Find the relative error in Z, if Z = CD 3 /2 Chapter - 3 [Motion in a Straight line] 1. The states of motion and rest are relative. Explain. 2. Give an example where the velocity of an object is zero, but its acceleration is not zero.

2 Chapter - 4 [Motion in a plane) 1. The vertical component of a vector is equal to its horizontal component. What is the angle made by the vector with X - axis. 2. What is the acceleration of a projectile at the top of its trajectory? 3. Can two vectors of unequal magnitude add up to give the zero vector? Can three unequal vectors addup to give the zero vector? 4. If A = i^ + j^, what is the angle between the vector and X - axis? 5. Two forces of magnitudes 3 units and 5 units acts at 60 with eachother. What is the magnitude of their resultant. Chapter - 5 [Laws of motion] 1. What is inertia? What gives the measure of inertia? 2. When a bullet is fired from a gun, the gun gives a kick in the backward direction. 3. Why does a rifle not recoil as strongly as a light rifle using the same catridges? 4. If a bomb at rest explodes into two pieces, the pieces must travel in opposite directions. Explain. 5. Can the coefficient of friction be greater than one? 6. Why does the car with a flattened tyre stop sooner than the one with inflated tyres? 7. A horse has to pull harder during the start of the motion than later - Explain. 8. What happens to the coefficent of friction, if the weight of the body is doubled. Chapter - 6 (Work - Energy - Power) 1. Define work, power, energy. State their SI units. 2. State the relation between kinetic energy and momentum of a body. 3. Which physical quantity remains constant (i) in an elastic collision (ii) in an inelastic collision. 4. A body freely falling from certain height 'h', after striking a smooth floor rebounds and h rises to a height of h/2. What is the coefficient of restitution between the floor and the body?

3 5. State the sign of work done by a force in the following. (a) work done by a man in lifting a bucket out of well by means of a rope tied to the bucket. (b) work done by gravitational force in the above case. 6. Find the angle between force and displacement F = 3 i^ + 4 j^ - 5 k^ S = 3 i^ + 4 j^ - 5 k^ Chapter - 7 [System of Particles and Rotational motion] 1. Is it necessary that a mass should be present at the centre of mass of any system. 2. Why are spokes provided in the bicycle wheel? 3. Two rigid bodies have same moment of inertia about their axes of symmetry or the two, which body will have greater kinetic energy? 4. Why do we prefer a spanner of longer arm as compared to the spanner of shortner arm? 5. Why should a helicopter necessarily have two propellers? 6. If the polar ice caps of the earth were to melt, what would the effect of the length of the day be? 7. Why is it easier to balance a bicycle in motion? 8. Find the scalar and vector product of two vectors a = 3 i^ - 4 j^ + 5 k^ b = -2 i^ + j^ - 3 k^ Chapter - 8 [Oscillations] 1. The displacement in S.H.M. is given by y = a sin (20t + 4). What is the displacement when it is increased by 2Π ω. 2. The bob of simple pendulum is a hallow sphere filled with water. How will be the period of oscillation change, if water begins to drain out of the hallow sphere. 3. The bob of pendulum is made of wood. What will be the effect on the time period, if the wooden bob is replaced by an identical bob of aluminium?

4 4. A pendulum clock gives correct time at equator. Will it gain or lose time if it is taken to the poles? If so why? 5. What happens to the energy of a simple hormonic oscillator. If its amplitude is doubled? 6. Can a simple pendulum be used in an artificial satellite? 7. On an average a human heart is found to beat 75 times in a minute. Calculate its frequency and period. Chapter - 9 (Gravitation) 1. State units and dimension of the gravitational constant (G). 2. What would be the change in acceleration due to gravity (g) at the surface, if the radius of earth decreases by 2% keeping the mass of earth constant? 3. Give the equation for the value of 'g' at a depth 'd' from the surface of earth. What is the value of 'g' at the centre of earth? 4. "Hyderogen is in abundance around the Sun but not around Earth" Explain. 5. What are polar satellites? 6. What is the time period of revolution of geostationary satellite? Does it rotate from West to East (or) from East to West? Chapter - 10 [Mechanical properties of solids] 1. State Hooke's law of elasticity. 2. State the units and dimensions of Young's modules. 3. Definite Hooks Law of Easticity, proportionality limit, permanent set and breaking stress. 4. State examples of nearly perfect elastic and plastic bodies. 5. Define Poisson's ratio, write its theoratical and practical limits. 6. A steel wire of length 20 cm is stretched to increase its length by 0.2 cm. Find the lateral strain in the wire if the poisson's ratio for steel is If an iron wire is stretched by 1% what is the strain on the wire? 8. ATungsten wire of length 20 cm is stretched by 0.1 cm. Find the strain on the wire? 9. A copper wire of 1mm diameter is stretched by applying a force of 10 N. Find the stress in the wire.

5 Chapter - 11 [Mechanical properties of fluids] 1. What is the Principle behind the Carburetor of an automobile? 2. What is magnus effect? 3. Why are drops and bubbles spherical? 4. Give the expression for excess pressure in an air bubble inside the liquid. 5. Give the expression for excess pressure inside the soap bubble in air. 6. What is angle of contact? 7. "Terminal velocity is more, if surface area of the body is more". Give reasons in support of your answer. 8. What are water proofing agents and water wetting agents? What do they do? 9. What is the pressure on a swimmer 10 m below the surface of a lake? 10. If the density of atmosphere at sea level is 1.29 Kg/m 3. Assume that it does not change with altitude. Then how high would the atmosphere extend? Chapter - 12 [Thermal properties of matter] 1. Distinguish between heat and temperature? 2. Can a substance contact on heating? Give an Example. 3. Why gaps are left between rails on a railway track? 4. Why utensils are coated with black? Why the bottom of utensils are made of copper? 5. Does a body radiate heat at 0 C? Does it radiate at 0 C? 6. Define co-efficient of thermal conductivity and temperature gradient. 7. What is greenhouse effect? Explain global warming. 8. State Newton's law of cooling? 9. State Weins displacement law? 10. What is specific gas constant, is it same for all gasses? 11. What is the temperature for which the readings on Kelvin and Fahrenheit scales are same?

6 Chapter - 13 (Thermodynamics) 1. Define thermal equillibrium. How does it lead to Zeroth law of thermodynamics? 2. Define Calorie. What is the relation between Calorie and mechanical equivalent of heat? 3. What thermodynamic variables can be defined by (a) Zeroth Law (b) First Law. 4. In Summer, when the valve of a bicycle tube is opened, the escaping air appears cold. Why? 5. A thermosflask containing a liquid is shaken vigorously, what happens to its temperature? 6. How much will be the internal energy change in (i) Isothermal Process (ii) Adiabatic Process. 7. What is the value of specific heat capacity in (i) Isothermal Process (ii) Adiabatic Process. 8. A refrigerator is to maintain eatables kept inside at 9 C. If room temperature is 36 C. Calculate the coefficient of performance. 9. Why does the breakdrum of an automobile get heated up, while moving down at constant speed? Chapter - 14 (Kinetic theory) 1. Define mean free path? 2. When does a real gas behave like an ideal gas? 3. What is the expression between pressure and kinetic energy of a gas molecule? 4. The absolute temperature of a gas is increased 3 times? What will be the increase in rms velocity of the gas molecules? 5. When pressure increases by 2%, what is the percentage decrease in the volume of a gas, assuming Boyle's law is obeyed? 6. If a gas has 'f' degrees of freedom, find the ratio of C p and C v.

7 4 Marks Questions (short answer type) Chapter - 3 [Motion in a straight line] 1. Can the equations of Kinematics be used when the acceleration varies with time? If not, what form would these equations take? 2. Show that the maximum height reached by a projectile launched at angle of 45 o is one quarter of its range. 3. A bullet is moving with a speed of 150 m/s strikes a tree and penetrates 3.5 cm before stopping. What is the magnitude of its retardation in the tree and the time taken for it to stop after striking the tree. 4. A ball is thrown vertically upwards with a velocity of 20 m/s from the top of a multistored building. The height of the point from where the ball is thrown is 25m from the ground. (a) How high will the ball rise? (b) How long will it be before the ball hits the ground? Take g = 10m/s A car moving along a straight highway with speed of 126 kmh -1 is brought to a stop within the distance of 200m. What is the retardation of the car, how long does it take for the car to stop? Chapter-(4) [Motion in a plane] 1. State Parallelogram law of vectors. Derive an expression for the magnitude and direction of the resultant vector. 2. If a + b = a - b, prove that the angle between a and b is Show that the trajectory of an object thrown at certain angle with the horizontal is parabola. 4. Explain the terms the average velocity and instantaneous velocity. When are they equal? u 2 sin 2 θ u 2 sin2θ 5. Show that maximum height and range of projectile are and 2g g respectively where the terms have their regular meanings. 6. A force 2 i^ - j^ - k^ newton acts on a body. Which is initially at rest. At the end of 20 seconds the velocity of the body is 4i^ + 2 j^ - 2k^ m/s. What is the mass of the body?

8 Chapter - 5 [Laws of motion] 1. Define the terms momentum and Impulse. State and explain the law of conservation of linear momentum. Give examples. 2. Why are shock absorbers used in motor cycles and cars? 3. Explain advantages and disadvantages of friction 4. Mention the methods used to minimise the friction 5. Why pulling the lawn roller preferred than pushing it? Chapter - 6 [Work - Power - Energy] 1. What is potential energy? Derive an expression for the gravitational potential energy. 2. Show that in case of one dimensional elastic collision, the relative velocity of approach of two colliding bodies before collision is equal to the relative velocity of separation after collision. 3. Show that two equal masses undergo oblique elastic collision will move at right angles after collision, if the second body initially at rest. 4. A machine gun fires 360 bullets per minute and each bullet travels with a velocity of 600 m/s. If the magnitude of each bullet is 5 gm. Find the power of machine gun? 5. Find the useful power used in pumping 3425 m 3 of water per hour from a well of 8m deep to the surface, suppose 40% of horse power during pumping is wasted. What is the horse power of engine? 6. A pump is required to lift 600 kg of water per min. from a well of depth 25m and to eject it with a speed of 50 m/s. Calculate the power required to perform the above task? 7. In a ballistic demonstration of police officer fires a bullet of mass 50gm with speed 200 m/s on soft plywood of thickness 2cm. The bullet emerges with only 10% of its initial kinetic energy. What is the emergent speed of the bullet?

9 Chapter - 7 [Systems of particles and rotational motion] 1. Distinguish between centre of mass and centre of gravity. 2. Explain about the centre of mass of Earth-Moon system and its rotation around the Sun. 3. Define vector product. Explain the properties of a vector product with examples. 4. Definie angular acceleration and Torque. Establish the relation between acceleration and Torque. 5. Find the centre of mass of three particles at the vertices of an equilateral triangle. The masses of the particles are 100gm, 150 gm, 200gm respectively. Each side of the equilateral triangle is 0.5 long. Find the Torque of the force (7 i^ - 3j^ - 5 k^) about the origin. The force acts on a particle whose position vector is ( i^ - j^ + k^ ) Chapter - 8 [Oscillations] 1. Obtain an equation for the frequency of oscillation of spring of force constant k to which a mass m is attached. 2. Define simple harmonic motion. Give two examples. 3. A particle executing SHM has amplitude of 4cm and its acceleration at a distance of 1 cm from the mean position is 3 cm/s 2. What will be the velocity at a distance of 2 cm from its mean position. 4. A Simple harmonic oscillator has a time period of 2 sec. What will be the change in phase 0.25 sec after leaving the mean position! 5. A freely falling body takes 2 seconds to reach the ground on a plane, when it is dropped from a height of 8m. If the period of a simple pendulum is Π seconds on the planet. Calculate the length of pendulum. Π 6. A body oscillates with SHM according to the equation x = 5cos [ 2Πt + ] At 4 t = 1.5 s, calculate the (a) displacement (b) speed (c) acceleration of the body.

10 Chapter - 9 [Gravitation] 1. State keplers laws of planetary motion. 2. What is orbital velocity? Obtain an expression for it. 3. What is escape velocity? obtain on expression for it. 4. What is geostationary satellite? State its uses. 5. Two spherical balls each of mass 1 kg are placed 1 cm apart. Find the gravitational force of attraction between them (G = 6.67 x Nm 2 /Kg 2 R = 6400 km) 6. A satellite is orbiting the earth at a height of 1000 km. Find its orbital speed. Chapter - 10 [Mechanical properties of solids] 1. Define Hooks law of elasticity, proportionality, permanent set, and breaking stress. 2. Define strain energy and derive the equation for the same. 3. Describe the behaviour of a wire under gradually increasing load. 4. Explain why the maximum height of a mountain on earth is approximately 10 km? Chapter - 11 [Mechanical properties of fluids] 1. What is pascals law and verify it with the help of an experiment. 2. Explain hydraulic lift and hydraulic brakes. 3. What is Toricelli's law? Explain how the speed of efflux is determined with an experiment. 4. What is venturi meter? Explain how it is used? 5. What is Reynold's number? What is its significance? 6. Explain dynamic lift with examples. Chapter - 12 [Thermal properties of matter] 1. In what way is the anomalous behaviour of water advantageous to acquatic animals. 2. A body cools from 60 to 40 in 7 min. What will be its temperature after next 7 min. If the temperature of its surroundigs is 10 C?

11 3. What is the temperature for which the readings on Kelvin and fahrenheit scales are same? 4. If the maximum intensity of radiation for a black body is found of 2.65 cm. What is the temperature of the radiating body? (Wein's constant = 2.9 x 10-3 mk) Chapter-13 (Thermodynamics) 1. Define two principal specific heats of a gas. Which is greater and why? 2. Derive the relation between two specific heat capacities of a gas on the basis of law of thermo dynamics. 3. Obtain an expression for the work done by an ideal gas during isothermal change. 4. Compare isothermal and adiabatic process. 5. Explain qualitatively the working of a heat engine. 6. State and expalin first law of thermodynamics Chatper - 14 (Kinetic theory) 1. Explain the kinetic interpretation of temperature. 2. Explain the concept of absolute zero of temperature on the basis of kinetic theory. 3. Four moles of gas have speeds 1, 2, 3 & 4 km/s. Find the rms speed of the gas molecule. 8 Marks Questions Chapter-5 [Law of motion] 1. (a) Define angle of friction and angle of repose. Show that angle of friction is equal to angle of repose for a rough inclined plane. (b) A block of mass 4 kg is resting on rough horizontal plane and is about to move when a horizontal force of 30N is applied on it. If g = 10 m/s 2. Find the total contact force exerted by the plane on the block. Chapter - 6 (Work - Energy - Power) 1. Develop the notations of work, Kinetic energy and show that it leads to work energy theorem. 2. State and prove Law of conservation of energy incase of a freely falling body.

12 Chapter - 7 [System of Particles and Rotational motion] 1. (a) State and prove parallel axes theorem (b) For a thin flat circular disc, the radius of gyration about a diameter as axis is k. If the disc is cut along a diameter AB (as shown in fig) into two equal pieces; then find the radius of gyration of each piece about AB. B 2. (a) State and Prove perpendicular axes theorem. A (b) If a thin circular ring and a thin flat circular disc of same mass have same moment of inertia about their respective diameters as axes. Then find the ratio of their radii. 3. State and Prove law of conservation of angular momentum. Explain the principle of conservation of angular momentum with examples. Chapter - 8 [Oscillations] 1. Define simple harmonic motion. Show that the motion of projetion of a prarticle performing uniform circular motion, on any diameter, is simple harmonic. 2. Show that motion of a simple pendulum is simple harmonic and hence derive an equation for its time period. What is seconds pendulum? Chapter - 9 (Gravitation) 1. State Newton's Law of Gravitation. Explain how the value of gravitational constant (G) can be determined by cavendish method. 2. Derive an expression for variation of acceleration due to gravity (g) (a) above (b) below the surface of earth. Chapter - 10 [Mechanical properties of solids] 1. Define Hook's Law of elasticity and describe an experiment to determine Young's modules of material of a wire. Chapter - 11 [Mechanical properties of fluids] 1. State Bernoulli's principle from conservation of energy in a fluid flow through a tube, derive Bernoulli's equation. Give an application of Bernoulli's theorem.

13 Chapter - 12 [Thermal properties of matter] 1. State Boyle's law and charles's Law. Hence derive ideal gas equation. Which of the two laws is better for the purpose of thermometry, why? 2. Explain thermal conductivity and coefficinet of thermal conductivity. A copper bar of thermal conductivity 401 w (mk) has one end at 104 o C and other end at 24 o C. The length of bar is 0.10 m, cross sectional area is 1.0 x 10-6 m 2 what is the rate of conduction, along the bar. Chapter - 13 (Thermodynamics) 1. Explain reversible and irreversible processes. Describe the working of carnot engine. Obtaion an expression for the efficency. - R. Sudha Rani