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

An ideal gas of density 1.7 × 10⁻³ g cm⁻³ at a pressure of 1.5 × 10⁵ Pa is filled in a Kundt's tube. When the gas is resonated at a frequency of 3.0 kHz, nodes are formed at a separation of 6.0 cm. Calculate the molar heat capacities C_p and C_v of the gas.

Given a + b + c + d = 0, state whether the following statement is correct or incorrect:

a, b, c, and d must each be a null vector.

A body describes simple harmonic motion with an amplitude of 5 cm and a period of 0.2 s. Find the acceleration and velocity of the body when the displacement is 5 cm.

A body describes simple harmonic motion with an amplitude of 5 cm and a period of 0.2 s. Find the acceleration and velocity of the body when the displacement is 3 cm.

Measure of two quantities along with the precision of respective measuring instrument is A = 2.5 ms^–1 ± 0.5 ms^–1 B = 0.10 s ± 0.01 s. The value of A B will be ______.

You measure two quantities as A = 1.0 m ± 0.2 m, B = 2.0 m ± 0.2 m. We should report correct value for `sqrt(AB)` as ______.

The mean length of an object is 5 cm. Which of the following measurements is most accurate?

The vernier scale of a travelling microscope has 50 divisions which coincide with 49 main scale divisions. If each main scale division is 0.5 mm, calculate the minimum inaccuracy in the measurement of distance.

Time for 20 oscillations of a pendulum is measured as t₁ = 39.6 s; t₂ = 39.9 s; t₃ = 39.5 s. What is the precision in the measurements? What is the accuracy of the measurement?

A physical quantity X is related to four measurable quantities a, b, c and d as follows: X = a² b³ c^5/2d^–2. The percentage error in the measurement of a, b, c and d are 1%, 2%, 3% and 4%, respectively. What is the percentage error in quantity X? If the value of X calculated on the basis of the above relation is 2.763, to what value should you round off the result.

A ball is dropped from a building of height 45 m. Simultaneously another ball is thrown up with a speed 40 m/s. Calculate the relative speed of the balls as a function of time.

It is a common observation that rain clouds can be at about a kilometre altitude above the ground.

1. If a rain drop falls from such a height freely under gravity, what will be its speed? Also calculate in km/h. ( g = 10 m/s²)
2. A typical rain drop is about 4mm diameter. Momentum is mass x speed in magnitude. Estimate its momentum when it hits ground.
3. Estimate the time required to flatten the drop.
4. Rate of change of momentum is force. Estimate how much force such a drop would exert on you.
5. Estimate the order of magnitude force on umbrella. Typical lateral separation between two rain drops is 5 cm.

(Assume that umbrella is circular and has a diameter of 1 m and cloth is not pierced through !!)

A man is standing on top of a building 100 m high. He throws two balls vertically, one at t = 0 and other after a time interval (less than 2 seconds). The later ball is thrown at a velocity of half the first. The vertical gap between first and second ball is +15 m at t = 2 s. The gap is found to remain constant. Calculate the velocity with which the balls were thrown and the exact time interval between their throw.

A, B and C are three non-collinear, non co-planar vectors. What can you say about direction of A × (B × C)?

A river is flowing due east with a speed 3 m/s. A swimmer can swim in still water at a speed of 4 m/s (Figure).

1. If swimmer starts swimming due north, what will be his resultant velocity (magnitude and direction)?
2. If he wants to start from point A on south bank and reach opposite point B on north bank, (a) which direction should he swim? (b) what will be his resultant speed?
3. From two different cases as mentioned in (a) and (b) above, in which case will he reach opposite bank in shorter time?

A proton is kept at rest. A positively charged particle is released from rest at a distance d in its field. Consider two experiments; one in which the charged particle is also a proton and in another, a positron. In the same time t, the work done on the two moving charged particles is ______.

A man squatting on the ground gets straight up and stand. The force of reaction of ground on the man during the process is ______.

A cubical block of density ρ is floating on the surface of water. Out of its height L, fraction x is submerged in water. The vessel is in an elevator accelerating upward with acceleration a . What is the fraction immersed?

We would like to make a vessel whose volume does not change with temperature (take a hint from the problem above). We can use brass and iron `(β_(vbrass) = (6 xx 10^(–5))/K and β_(viron) = (3.55 xx 10^(–5))/K)` to create a volume of 100 cc. How do you think you can achieve this.

We would like to make a vessel whose volume does not change with temperature (take a hint from the problem above). We can use brass and iron `(β_(vbrass) = (6 xx 10^(–5))/K and β_(viron) = (3.55 xx 10^(–5))/K)` to create a volume of 100 cc. How do you think you can achieve this.