Science (English Medium) कक्षा ११ - CBSE Question Bank Solutions for Physics

Two cylinders A and B of equal capacity are connected to each other via a stopcock. A contains a gas at standard temperature and pressure. B is completely evacuated. The entire system is thermally insulated. The stopcock is suddenly opened. Answer the following:

What is the change in the temperature of the gas?

Which of the following functions of time represent (a) simple harmonic, (b) periodic but not simple harmonic, and (c) non-periodic motion? Give period for each case of periodic motion (ω is any positive constant):

sin ωt – cos ωt

Which of the following functions of time represent (a) simple harmonic, (b) periodic but not simple harmonic, and (c) non-periodic motion? Give period for each case of periodic motion (ω is any positive constant):

sin³ ωt

Which of the following functions of time represent (a) simple harmonic, (b) periodic but not simple harmonic, and (c) non-periodic motion? Give period for each case of periodic motion (ω is any positive constant):

3 cos `(π/4 – 2ω"t")`

Which of the following functions of time represent (a) simple harmonic, (b) periodic but not simple harmonic, and (c) non-periodic motion? Give period for each case of periodic motion (ω is any positive constant):

cos ωt + cos 3ωt + cos 5ωt

Which of the following functions of time represent (a) simple harmonic, (b) periodic but not simple harmonic, and (c) non-periodic motion? Give period for each case of periodic motion (ω is any positive constant):

exp (–ω²t²)

Which of the following functions of time represent (a) simple harmonic, (b) periodic but not simple harmonic, and (c) non-periodic motion? Give period for each case of periodic motion (ω is any positive constant):

1 + ωt + ω²t²

Use the formula `v = sqrt((gamma P)/rho)` to explain why the speed of sound in air is independent of pressure.

Use the formula `v = sqrt((gamma P)/rho)` to explain why the speed of sound in air increases with temperature.

A bat emits an ultrasonic sound of frequency 1000 kHz in the air. If the sound meets a water surface, what is the wavelength of the the reflected sound? The speed of sound in air is 340 m s^–1 and in water 1486 m s^–1.

For the travelling harmonic wave

y (x, t) = 2.0 cos 2π (10t – 0.0080x + 0.35)

Where x and y are in cm and t in s. Calculate the phase difference between oscillatory motion of two points separated by a distance of 4 m.

For the travelling harmonic wave

y (x, t) = 2.0 cos 2π (10t – 0.0080x + 0.35)

Where x and y are in cm and t in s. Calculate the phase difference between oscillatory motion of two points separated by a distance of 0.5 m.

For the travelling harmonic wave

y (x, t) = 2.0 cos 2π (10t – 0.0080x + 0.35)

Where x and y are in cm and t in s. Calculate the phase difference between oscillatory motion of two points separated by a distance of `λ/2`.

For two vectors A and B, A + B = A − B is always true when

1. |A| = |B| ≠ 0
2. A ⊥ B
3. |A| = |B| ≠ 0 and A and B are parallel or anti parallel
4. When either |A| or |B| is zero

Given below in column I are the relations between vectors a, b and c and in column II are the orientations of a, b and c in the XY plane. Match the relation in column I to correct orientations in column II.

Column I			Column II
(a)	a + b = c	(i)
(b)	a – c = b	(ii)
(c)	b – a = c	(iii)
(d)	a + b + c = 0	(iv)

A car of mass m starts from rest and acquires a velocity along east `v = vhati (v > 0)` in two seconds. Assuming the car moves with uniform acceleration, the force exerted on the car is ______.

A body of mass 10 kg is acted upon by two perpendicular forces, 6 N and 8 N. The resultant acceleration of the body is ______.

1. 1 m s^–2 at an angle of tan⁻¹ `(4/3)` w.r.t 6 N force.
2. 0.2 m s^–2 at an angle of tan⁻¹ `(4/3)` w.r.t 6 N force.
3. 1 m s^–2 at an angle of tan⁻¹ `(3/4)` w.r.t 8 N force.
4. 0.2 m s^–2 at an angle of tan⁻¹ `(3/4)` w.r.t 8 N force.

A mass of 2 kg is suspended with thread AB (Figure). Thread CD of the same type is attached to the other end of 2 kg mass. Lower thread is pulled gradually, harder and harder in the downward directon so as to apply force on AB. Which of the threads will break and why?

In the above given problem if the lower thread is pulled with a jerk, what happens?

Block A of weight 100 N rests on a frictionless inclined plane of slope angle 30° (figure). A flexible cord attached to A passes over a frictonless pulley and is connected to block B of weight W. Find the weight W for which the system is in equilibrium.