CBSE Class - XI Physics Last year Paper (2015-16)

Time: 3 Hrs. M.M: 70

General Instructions:

1. Question 1 to 5 one mark.
2. Question 6 to 10 each two mark.
3. Question 11 to 22 each three mark.
4. Question 23 is value based question and carry four marks.
5. Questions 24 to 26 each five mark.

Section A

All constants are dimensionless. Comment.

1. When can an object in motion be considered as a point object?
2. A particle is moving in a straight line. Is it possible for it to maintain the motion in the same direction while the acceleration is in the reverse direction.
3. On what factors does the value of angle of contact depend?
4. Plot a graph showing the variation of specific heat of water with temperature.

Section B

1. What are the important steps involved in a scientific method to understand a natural phenomenon?
2. Determine the maximum acceleration of the train in which a box lying on its floor will remain stationary, given that the coefficient of the static friction between the box and the train's floor is 0.15.
3. State and explain work-energy theorem.
4. The excess pressure inside a soap bubble is thrice the excess pressure inside a moving soap bubble. What is the ratio between the volume of the first and second bubble?
5. State the principle of superposition of waves. What happens when phase differences between two waves are (i) 0 and (ii) <math>\pi</math>?

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<math>\mathbf{or}</math>

A harmonic oscillator is oscillating with a frequency of 3 Hz. Its acceleration amplitude is <math>0.36\pi^2 m/s^2</math>. Determine its velocity amplitude and the amplitude of displacement.

Section C

1. What are systematic errors? What is their cause? How can these be minimised?

1. A 100 m sprinter uniformly increases his speed from rest at the rate of <math>1m/s^2</math> up to <math>\frac{3}{4}th</math>

of the total run and then covers the balance <math>\frac{1}{4} th</math> run with uniform speed. 4 How much time does he take to complete the race?

1. An object of mass m is moving in a circular motion of radius r at a constant speed v. Obtain an expression for the magnitude of acceleration of the object.
2. Find the instantaneous acceleration of a 1.0 kg mass suspended from a spring constant of force constant 5.0 N/cm, when the spring is stretched 10.0 cm. The mass is initially at rest.
3. How can you show that when a particle suffers an oblique elastic collision with another particle of equal mass and initially at rest, the two particles would move in mutually perpendicular directions after collision?
4. How is angular velocity related to linear velocity of a particle of the body in rotational motion? Does pure rotation take place at uniform velocity or at uniform linear velocity?
5. A mass m is placed at P a distance h along the normal through the centre O of a thin circular ring of mass m and radius r as shown in figure.

n m If the mass is removed further away such that OP becomes 2h, by what factor the force of gravitation will decrease, if h = r?

1. Two identical solid ball, one of irony and the other of wet clay are dropped from the same

height on the floor. Which one will rise to a greater height after striking the floor and why? or 2/5