Physics Question Paper - September Exam

PHYSICS

September Examination

Time Allowed: 3 Hours Maximum Marks: 70

General Instructions:

There are 19 questions in total. All questions are compulsory.
This question paper has five sections: Section A, Section B, Section C, Section D, and Section E.
Section A contains Question 1 having 16 multiple-choice sub-parts of 1 mark each.
Section B contains 6 questions (Q2 to Q7) of 2 marks each. Internal choice is provided in two questions.
Section C contains 8 questions (Q8 to Q15) of 3 marks each. Internal choice is provided in two questions.
Section D contains 1 case-based study question (Q16) of 3 marks.
Section E contains 3 long-answer questions (Q17 to Q19) of 5 marks each. Internal choice is provided in all three questions.
Total weightage of numericals is approximately 20%.
Use of an un-programmable calculator is allowed. Log tables can be used.

SECTION A (16 Marks)

Q1. Multiple Choice Questions. Choose the most appropriate option. (1 × 16 = 16)

(i) 1 metre is equal to:

(a) 10¹⁰ Å
(b) 10⁸ Å
(c) 10⁶ Å
(d) 10⁵ Å

(ii) Joule × sec is the unit of:

(a) energy
(b) momentum
(c) angular momentum
(d) power

(iii) KWh is a unit of:

(a) power
(b) energy
(c) force
(d) temperature

(iv) One astronomical unit is the distance between:

(a) Moon and the Earth
(b) Mars and the Earth
(c) Sun and the Earth
(d) Sun and Pluto

(v) If the distance covered is zero, the displacement:

(a) Cannot be zero
(b) Must be zero
(c) May or may not be zero
(d) depends on other factors

(vi) The area under velocity-time graph for a particle in a given interval of time represents:

(a) Speed
(b) Displacement
(c) Average Velocity
(d) Acceleration

(vii) SI unit of acceleration is:

(a) ms^-1
(b) ms^-3
(c) ms^-2
(d) m²s^-2

(viii) A stone is just released from the window of a train moving along a horizontal straight track. The stone will hit the ground following a:

(a) Straight line path
(b) Circular path
(c) Parabolic path
(d) Hyperbolic path

(ix) Speedometer of a car can measure:

(a) Instantaneous speed
(b) Instantaneous velocity
(c) Angular acceleration
(d) Linear velocity

(x) S.I unit of displacement is:

(a) ms^-1
(b) ms^-2
(c) m
(d) cm

(xi) A man getting down a running bus falls forward because:

(a) Due to inertia of rest, road is left behind and man reaches forward.
(b) Due to inertia of motion upper part of body continues to be in motion in forward direction while feet come to rest as soon as they touch the road.
(c) He leans forward as a matter of habit.
(d) Of the combined effect of all the three factors stated (a), (b) and (c).

(xii) A 1000kg spaceship travels in the vacuum of space at a constant speed of 500m/s. Ignoring any gravitational forces, what is the net force on the spaceship?

(a) 500000 N
(b) 2 N
(c) 0.5 N
(d) 0 N

(xiii) 1 Newton =

(a) 10⁵ dyne
(b) 10^-5 dyne
(c) 980 dyne
(d) None of these

(xiv) The working of a rocket is based on the principle of:

(a) Elasticity
(b) Kepler’s Law
(c) Newton’s 1st Law
(d) conservation of momentum

(xv) What is the SI unit of Work?

(a) Joule
(b) erg
(c) g-cm
(d) Watt

(xvi) What happens to its potential energy when an object is taken to a high altitude?

(a) Its potential energy increases
(b) Its potential energy decreases
(c) Its potential energy remain same
(d) None of the above

SECTION B (12 Marks)

Q2. Write the characteristics of a standard unit. (2)

Q3. Can a body have a constant speed but a varying velocity? Explain briefly. (2)

Q4. A man moving in rain holds his umbrella inclined to the vertical even though the raindrops are falling vertically downwards. Why?

Can a vector be zero, if one of its components is non-zero? (2)

Q5. Action and reaction are equal and opposite to each other, yet they don't cancel each other. Why? (2)

Q6. Why are the wheels of vehicles provided with mudguards?

How does friction help us in walking? (2)

Q7. How will the momentum of a body change if its kinetic energy is doubled? (2)

SECTION C (24 Marks)

Q8. Name the fundamental units and supplementary units in SI along with their symbols of representation. (3)

Q9. What is meant by significant figures? Give any four rules for counting significant figures.

Check the accuracy of the relation ν = (1/2l)√(T/m), where ν is frequency, l is length, T is tension in the string and m is mass per unit length of the string. (3)

Q10. Derive the expression for the distance covered by an object in the n^th second of its motion.

A player throws a ball upwards with an initial speed of 29.4 ms^-2. To what height does the ball rise and after how long does the ball return to the player’s hands? (Take g = 9.8 ms^-2 and neglect air resistance). (3)

Q11. Find the expression for (i) Time of flight and (ii) Horizontal range of a projectile given an angular projection. (3)

Q12. State the law of conservation of linear momentum. Explain why a gun recoils after firing. (3)

Q13. What is meant by banking of a road? Obtain an expression for the angle of banking of a road. (3)

Q14. Prove that the mechanical energy of a freely falling object always remains constant. Also, make a graph showing the variation of Kinetic Energy (KE), Potential Energy (PE), and Total Energy (TE) with the position of the object. (3)

Q15. A tube well pumps out 2400 kg of water per minute. If water is coming out with a velocity of 3 ms^-1, what is the power of the pump? How much work is done if the pump runs for 10 hours? (3)

SECTION D (3 Marks)

Q16. Case-Based Study Question (3)

Read the following paragraph and answer the questions that follow:

This principle is a consequence of Newton’s second and third laws of motion. In an isolated system (i.e., a system having no external force), mutual forces (called internal forces) between pairs of particles in the system causes momentum change in individual particles. Let a bomb be at rest, then its momentum will be zero. If the bomb explodes into two equal parts, then the parts fly off in exactly opposite directions with same speed, so that the total momentum is still zero. Here, no external force is applied on the system of particles.

(i) A shell of mass 10 kg is moving with a velocity of 10 ms^-1 when it blasts and forms two parts of mass 9 kg and 1 kg respectively. If the first mass is stationary, the velocity of the second is:

(a) 1 m/s
(b) 10 m/s
(c) 100 m/s
(d) 1000 m/s

(ii) A bullet of mass 10 g is fired from a gun of mass 1 kg with a recoil velocity of gun 5 m/s. The muzzle velocity will be:

(a) 30 km/min
(b) 60 km/min
(c) 30 m/s
(d) 500 m/s

(iii) Two masses of M and 4M are moving with equal kinetic energy. The ratio of their linear momenta is:

(a) 1:8
(b) 1:4
(c) 1:2
(d) 4:1

SECTION E (15 Marks)

Q17. Define astronomical unit, light year and parsec. Establish the relation between them.

Explain the uses of dimensional equations giving at least one example in each case. (5)

Q18. Derive the following equations of motion using the graphical method:
(i) v = u + at
(ii) S = ut + ½at²
(iii) v² - u² = 2as

State the parallelogram law of vector addition. Explain it in detail, including analytical treatment to find the magnitude and direction of the resultant vector. (5)

Q19. State and explain Newton’s third law of motion. Give at least two illustrations. Prove the principle of conservation of linear momentum using this law.

Discuss elastic collision in one dimension. Derive the expressions for the velocities of two bodies after such a collision. (5)