## Kerala Plus One Physics Model Question Paper 2

Time: 2 Hours

Cool off time: 15 Minutes

Maximum: 60 Scores

General Instructions to candidates

- There is a ‘cool off time’ of 15 minutes in addition to the writing time.
- Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
- Read the instructions carefully.
- Read questions carefully before you answering.
- Calculations, figures, and graphs should be shown in the answer sheet itself.
- Malayalam version of the questions is also provided.
- Give equations wherever necessary.
- Electronic devices except non-programmable calculators are not allowed in the Examination Hall.

Questions 1 – 5 carry 1 score each. Answer any four questions.

Question 1.

What is the range of weak nuclear force?

Question 2.

During isothermal expansion the internal energy of gas became ………………

Question 3.

The main mode of transmission of heat by which the sun heats the surface of the earth is ……………

- Conduction
- Convection
- Radiation
- None of these

Question 4.

A constant force of 200 N displaces a body through 5 m in the direction of the force. Find the work done on the body.

Question 5.

Say true/false: “ All the false conductors are electrical conductors also”.

Questions 6 to 11 carry 2 scores each. Answer any 5 questions.

Question 6.

A physical quantity is given by A = \(h=\frac { { Fv }^{ 2 } }{ L }\). F is the force, v is the velocity and L is the angular momentum. Find the dimensions of h.

Question 7.

Position time graph of a body is given.

a. Estimate the velocity during the time interval t = 2s to t = 3s.

b. Displacement of an object is proportional to t^{3}. Show that its acceleration is increasing with time.

Question 8.

One mole of an ideal gas expands from volume V_{1} to Volume V_{2} at a constant temperature T. Derive an expression for the work done.

Question 9.

The stress-strain graphs for two materials A and B are shown below (the graphs are drawn using the same scale) Which of the two is the stronger material?

Question 10.

A brass tumbler feels much colder than a wooden tray on a chilly day. Why?

Question 11.

Three vessels of different shapes are filled with water to the same height ‘h’ and their bottom parts are connected to manometers measuring the pressure. The water levels in ail the vessels remain the same.

a. Identify the above phenomenon.

b. Predict the pressure level shown by the manometers.

Questions 1217 carry 3 scores each. Answer any five questions.

Question 12.

a. The error in the measurement of the radius of a circle is 0.6%. Find the percentage error in the calculation of the area of the circle.

b. What is the number of significant figures in 0.00820 J?

Question 13.

A simple pendulum is an object suspended by a weightless and inextensible string fixed rigidly to support.

- Under what conditions for the amplitude, are the oscillations of the pendulum simple harmonic?
- The period of oscillation of the pendulum is T. What will be the period if the pendulum is suspended in a lift moving down with an acceleration equal to g/3.2

Question 14.

a. Will the passenger experience a decrease or an increase in his weight? Explain.2

b. What will be the effect if the cable is cut and the lift falls freely?

Question 15.

Elasticity is the property of matter that is characterized by atomic packing. For an elastic solid, stress applied is directly proportional to the strain produced in it. The stress versus strain graph for three materials A, B and C is shown below.

a. Which is more elastic A, B or C? Justify your answer.

b. If the bulk modulus of water is 2 × 10^{8} Nnr^{-2}. Find its compressibility.

Question 16.

When a mass is suspended on a metallic wire, the length of the wire increases slightly.

a. Name and state the law that relates to the restoring force developed in the wire and its deformation.

b. Draw the stress-strain graph of a loading wire. Mark the following points:

- Elastic limit
- Fracture point
- Plastic region
- Elastic region.

Question 17.

Gases have two specific heat capacities, C and Cv. Why?

b. Laplace pointed out that when sound is propagating through a gaseous medium, the change is adiabatic. Show that adiabatic bulk modulus is yΔp.

Questions 18 to 22 carry 4 scores each. Answer any 4 questions.

Question 18.

A rigid body is a body with a perfectly unchanging shape under the influence of an external force.

a. What do you mean by the center of mass of a rigid body?

b. A rigid beam of length L, breadth band depth d is supported near its ends as shown in the figure. A load W is suspended at its center of mass. Write the expression for the amount of sagging.

c. A steel beam of length 5 m is kept at a temperature of 20°C. On a hot day, the temperature rises to 40°C. What is the change in its length due to thermal expansion? (Coefficient of linear expansion of steel is 1.2 × 10^{-5}/°C).

Question 19.

Our earth has several artificial satellites. But the moon is the only natural satellite.

a. If acceleration due to gravity at the surface of the earth is ‘g’, arrive at the expression for acceleration due to gravity at a depth’.

b. Distance to the moon from the earth is 3.84 × 10^{8} m and the time period of the moon’s revolution is 27,3 days. Obtain the mass of the earth. (g = 6.67 × 10^{-11} Nm^{2}/kg^{2})

Question 20.

The rotational analog of force is a moment of force, also called torque.

a. The turning effect of the force is maximum when the angle between? and p is …………..

b. A wheel starting from rest acquires an angular velocity of 10 rad/s in two seconds. The moment of inertia of the wheel is 0.4 kg m^{2}. Calculate the torque acting on it.

Question 21.

When a horse suddenly starts moving, the rider falls backward.

a. Name and state the law used to explain the above theorem.

b. State the law of conservation of linear momentum and prove it on the basis of the second law of motion.

Question 22.

Viscosity is the frictional force in fluids.

a. When a small metal ball is falling through a viscous medium, what are the various forces acting on it? Using this arrive at an expression for terminal velocity.

b. Raindrops falling under gravity do not acquire very high velocity. Why?

Questions from 2326 carry 4 scores. Answer any 3 questions.

Question 23.

a. A heat engine is a device used to convert energy into energy.

b. Name the four processes taking place in the Carnot cycle. Draw indicator diagram of the Carnot cycle.

c. A hole is drilled in a copper sheet. The diameter of the hole is 4.24 cm at 27°C. What is the change in diameter of the hole when the sheet is heated to 227° C? (Coefficient of linear expansion of copper = 1.7 x 10^{-5}/°C)

d. Write four postulates of kinetic theory of gases.

Question 24.

The antiseptics used for cuts and wounds in human flesh have low surface tension. Due to low surface tension, they spread over the wounds easily.

a. In the following figure, the angle of contact 0 is

b. Surface tension causes capillarity. Define capillarity and arrive at the expression for a capillary rise in terms of surface tension.

c. In a capillary tube, water rises to a height. If the capillary tube is inclined at an angle 60° with the vertical, what will be the length of the water column in the tube?

Question 25.

Moment of inertia is the analog of mass in rotational motion. But unlike mass, it is not a fixed quantity.

a. Moment of inertia can be regarded as a measure of rotational inertia. Why?

b. Write any two factors on which the moment of inertia of a rigid body depends.

c. The moments of inertia of two rotating bodies A and B are lAand lB, (lA > lB) and their angular momentum is equal. Which one has greater kinetic energy? Explain.

Question 26.

The outer side of a circular track of radius 200 m is raised to make an angle of 15°

a. Which force provides the necessary cen tripetal force for a car taking the circular track?

b. Name the process by which the outer side of a curved track is raised a little above the inner side.

c. Using the data provided in this case, determine the maximum permissible speed to avoid skidding. (Given ps = 0.25)

Answers

Answer 1.

The range of a nuclear force is of the order of 10^{-16}m.

Answer 2.

Zero

Answer 3.

Radiation.

Answer 4.

Force = 200 N displacement = 5m

Work done = Force × displacement = 200 × 5 = 1000 J

Answer 5.

False

Answer 6.

Answer 7.

i.e., a α t, Hence acceleration increases with time.

Answer 8.

PV = nRT; here n = 1

We have a small amount of work done when volume changes through tv at pressure p. Let volume change from V_{1} to V_{2 }isothermally,

Answer 9.

Material A is stronger than material B because it can withstand more load without breaking for material A, the break-even point (D) is higher.

Answer 10.

The thermal conductivity of brass tumbler is larger than a wooden tray. Hence a brass tumbler feels much colder than a wooden tray.

Answer 11.

a.Hydrostatic paradox.

b. Pressure at the same height is the same.

Answer 12.

b. 3

Answer 13.

1. Amplitude should be small.

2. The period of simple pendulum \(T=2\pi \sqrt { \frac { 1 }{ g } }\)

When a lift is moving down with an acceleration g/3.

Answer 14.

a. The passenger experiences a decrease in weight.

b. The passenger experiences weightlessness W’ = m (g – g) = 0

Answer 15.

a. Material A is more elastic. Because the strain of material A is smaller than that other and slope of A is more. Soan extension of A will be less than B and C. When they are subjected to same reforming force F.

Answer 16.

a. Hooke’s law. Hooke’s law states that when elastic limit stress is directly proportional to strain.

Answer 17.

a. Heat can be given to gas in two ways.

1. By keeping the pressure constant.

2. By keeping volume constant. In (1) gas expands, additional heat is needed to work.

Answer 18.

a. Centre of a mass of a rigid body in the point where the whole mass of the body is assumed to be concentrated.

Answer 19.

Answer 20.

Answer 21.

a. Newton’s 1st Law of motion. The law states that “ everybody continues in its state of rest or of uniform motion in a straight line unless compelled by some external unbalanced force to change that state”,

b. The law states that “ If no external force acts on a system of several particles, the total linear momentum of the system remains constant”.

Answer 22.

a. The constant speed of the object falling through a viscous medium is called terminal velocity. The vicious force, F = 6xr|rv Considering the motion of the body, viscous force = apparent weight of the object in the fluid. where 5 is the density of the material of the solid and a that of the fluid.

b.Rain drop falling under gravity is acted upon by weight, upthrust and viscous force. Hence it attains constant velocity.

Answer 23.

a. Heat energy into mechanical energy.

b. Isothermal expansion AB Adiabatic expansion BC Isothermal compression CD Adiabatic compression DA

d.

1. Gas molecules randomly move all the time and collide with each other and with walls of a container.

2. Size of molecules is negligible compared to the average distance between molecules.

3. Molecules are rigid spheres with no attraction or repulsion between themselves or container and so, all the internal energy is kinetic.

4. A collision between molecules and wall are elastic. In between collisions they move in straight lines with uniform velocity. Time of collision is very small compared to time available for free motion.

Answer 24.

a. Obtuse or θ > 90°

The capillary action is a result of both adhesion and surface tension. If a capillary tube is held vertical in a liquid which has a concave meniscus. There always exists an excess pressure equal to 2s/R on the concave side of liquid are interphase. Where ‘S’ is the surface tension and R is the radius of curvature of a meniscus. Pressure just below the meniscus is p 2s/R, where P is the atmospheric pressure. The pressure outside the tube at a level of the meniscus is the atmospheric pressure’P’. Since the pressure at points in the same level of liquid must be the same, the liquid is pushed up in the tube to the height ‘h’ as shown in fig(a). In this position, the pressure of liquids column of height ‘h’ becomes equal to 2s/R. ∴ \(hpg=\frac { 2s }{ R }\) where p is the density and ‘g’ is an acceleration due to gravity.

From fig (b)

l = 2h or length increases.

Answer 25.

a. Just as inertia resists translatory motion, when a rigid body rotates about an axis, there is a tendency to resist changes in uniform rotational motion. Moment of inertia resists change in rotational motion of the body.

b. Moment of inertia of a rigid body depends on the mass of particles and the distribution of particles about the axis of rotation, size, and shape.

Answer 26.

a. It is provided by the force of friction between the tires of the car and the road.

b. Banking of roads.