Physics
Question from maharashtra board physics book of 12th maharashtra board
- Write ideal gas equation for a mass of 7 g of nitrogen gas. In the usual notation, PV =nRT. n= Mass of the gas/Molar Mass =7/28= 1/4 Therefore, the corresponding ideal gas equation is PV = 1/4 RT. 1
- On what factors do the degrees of freedom depend? The degrees of freedom depends upon the structure of the molecule the temperature of the gas. the number of atoms forming a molecule 1
- What will happen to the mean square speed of the molecules of a gas if the temperature of the gas increases? If the temperature of a gas increases, the mean square speed of the molecules of the gas will increase in the same proportion. V^(2 )= 3nRT/... 1
- The ratio of emissive power of perfectly blackbody at 1327° C and 527 °C is (A) 4:1 (B) 16 : 1 (C) 2 : 1 (D) 8 : 1 (B) 16 : 1 The ratio of emissive power of perfectly blackbody at 1327° C and 527 °C is 16 : 1 1
- If a = 0.72 and r = 0.24, then the value of tr is (A) 0.02 (B) 0.04 (C) 0.4 (D) 0.2 (B) 0.04 tr=1-a-r =1-0.72-0.24 =0.04 2
- If pressure of an ideal gas is decreased by 10% isothermally, then its volume will (A) decrease by 9% (B) increase (D) increase by 11.11% 2
- The mean free path λ of molecules is given by C) 1/√(2)πnd² 1
- i) In an ideal gas, the molecules possess (A) only kinetic energy (B) both kinetic energy and potential energy (A) only kinetic energy 2
- Why is the surface tension of paints and lubricating oils kept low? Answer: so that paints and lubricating oils spread easily and wet the surface well. A liquid with high surface tension tends to pull itself... 1
- In Bernoulli’s theorem, which of the following is conserved? (A) linear momentum (B) angular momentum (C) mass (D) energy In Bernoulli’s theorem, Energy is conserved 2
- Two hail stones with radii in the ratio of 1:4 fall from a great height through the atmosphere. (C) 1:16 Two hail stones with radii in the ratio of 1:4 fall from a great height through the atmosphere. Then the ratio of their terminal ve... 1
- The energy stored in a soap bubble of diameter 6 cm and T = 0.04 N/m is nearly (A) 0.9 × 10-3 J (B) 0.4 × 10-3 J (A) 0.9 × 10⁻³ J The energy stored in a soap bubble of diameter 6 cm and T = 0.04 N/m is nearly 0.9 × 10⁻³ J 1
- Two capillary tubes of radii 0.3 cm and 0.6 cm are dipped in the same liquid. B) 2:1 Two capillary tubes of radii 0.3 cm and 0.6 cm are dipped in the same liquid. The ratio of heights through which the liquid will rise... 1
- A hydraulic lift is designed to lift heavy objects of maximum mass 2000 kg. The area of cross section of piston (A) 0.8711 × 10⁶ N/m^(2 ) 2
- Find the radius of gyration of a uniform disc about an axis perpendicular to its plane and passing through its center Answer: K = R/√(2) ≈ 0.707 R The moment of inertia of a uniform disc of mass M and radius R about an axis through its centre and perpendicul... 1
- A rectangular wire frame of size 2 cm x 2 cm, is dipped in a soap solution and taken out. Answer: 3x10⁻⁵ J or 30μJ Explaination: A2=3x3=9 and A1= 2x2=4 Area are in cm² let convert it to m² A2=9x10⁻⁴ and A1=4x10⁻⁴ , T=3x10⁻² The ex... 1
- How much work is required to form a bubble of 2 cm radius from the soap solution having surface tension 0.07 N/m. Answer= 0.703× 10-3 J \ \ \ or \ \ \ 7.038× 10⁻⁴ J Explaination:: Given:: Radius of the bubble = 2 cm or 0.02 m Surface tension = 0.07 N/m S... 1
- A drop of mercury of radius 0.2 cm is broken into 8 droplets of the same size. Find the work done if the surface tension of mercury is 435.5 dyne/cm Answer:: 2.19 x 10⁻⁵ J Explaination:: Given :: R = 0.2 cm, n = 8, T = 435.5 dyn/cm As the volume of the liquid remains constant, volume of n... 1
- Twenty seven droplets of water, each of radius 0.1 mm coalesce into a single drop. Find the change in surface energy. Surface tension of water is 0.072 N/m. Correct answer = 1.628 x 10⁻⁷ J Explaination :: Given :: r=0.1mm =0.1 x 10⁻³m , T=0.072 N/m Let R be the radius of the single drop formed du... 1
- An air bubble of radius 0.2 mm is situated just below the water surface. Calculate the gauge pressure. Surface tension of water = 7.2x 10-2 N/m. Correct Answer: 720 N/m² Explaination:: Given : Radius of bubble =0.2 mm = 2× 10⁻⁴ m , surface tension of water = 0.072 N/m = 720× 10⁻⁴ N/m... 1
- Calculate the rise of water inside a clean glass capillary tube of radius 0.1 mm, when immersed in water of surface tension 7x10-2 N/m. Correct Answer = 0.142 m Explaination Given:: r = 0.1 mm = 10⁻⁴ m, T = 7 × 10⁻² N/m, θ = 0°, ρ = 1000 kg/m³, g = 9.8 m/s^(2 ) To find: Heigh... 1
- The pressure of water inside the closed pipe is 3 x105 N/m2. This pressure reduces to 2x105 N/m2 on opening the value of the pipe. Correct answer = 14.14 m/s Explaination:: Given:: p₁ = 3 × 10⁵ Pa, v₁ = 0, p₂ = 2 × 10⁵ Pa, ρ = 10³ kg/m³ Assuming the potential head to be... 1
- With what velocity does water flow out of an orifice in a tank with gauge pressure 4 x105 N/m2 before the flow starts? Correct answer= 28.28 m/s Explaination Given:: p - p₀ = 4 × 10⁵ Pa, ρ = 10³ kg/m³ If the orifice is at a depth h from the water surface in a... 1
- The speed of water is 2m/s through a pipe of internal diameter 10 cm. Correct answer =7.07 x 10⁻² m Explaination:: Given : d1=10cm =0.1 m , v1=2m/s, v2=4m/s Solution: by the equation of continuity , the ratio o... 1