Class 11 PhysicsImportant Questions for Board Exams 2025-26

Name the four fundamental forces of nature. Which is the strongest and which is the weakest?

What do you mean by the scope of physics? Give two examples each from macroscopic and microscopic domains.

What is the principle of conservation of energy? State its universal applicability.

Distinguish between the gravitational force and the electromagnetic force in terms of their range and relative strength.

What are the limitations of dimensional analysis?

The period of a simple pendulum depends on length l and acceleration due to gravity g. Using dimensional analysis, derive the formula for the time period.

The resistance R = V/I, where V = (100 ± 2) V and I = (10 ± 0.2) A. Find the percentage error in R.

Explain with an example how significant figures indicate the precision of a measurement.

Distinguish between systematic errors and random errors. How can each be minimised?

A ball is thrown vertically upward with velocity 49 m/s. Find (i) maximum height reached, (ii) time of flight. (g = 9.8 m/s²)

Draw velocity-time graphs for uniform motion and uniformly accelerated motion. How is displacement calculated from the v-t graph?

A car starts from rest and accelerates uniformly at 2 m/s². Find its velocity and displacement after 10 s.

Define instantaneous velocity. How is it different from average velocity?

Two trains A and B are moving in the same direction with speeds 80 km/h and 50 km/h respectively. Find the velocity of train A relative to train B.

Derive the three equations of uniformly accelerated motion using the velocity-time graph.

A projectile is launched with velocity 20 m/s at 30° to the horizontal. Find the maximum height, time of flight, and horizontal range. (g = 10 m/s²)

Prove that the trajectory of a projectile is parabolic.

Define centripetal acceleration. Derive an expression for centripetal acceleration for uniform circular motion.

Find the resultant of two vectors of magnitudes 3 N and 4 N acting at right angles to each other.

What is the angle of projection for which the horizontal range is equal to the maximum height?

State Newton's Second Law of motion. How does it reduce to the First Law when F = 0?

A block of mass 5 kg is on a rough horizontal surface (μ_k = 0.3). A horizontal force of 25 N is applied. Find the acceleration. (g = 10 m/s²)

Derive the law of conservation of linear momentum from Newton's Third Law.

Explain why a person jumping from a moving bus should run in the direction of the bus after landing.

A bullet of mass 50 g moving at 400 m/s is embedded in a block of mass 950 g at rest. Find the common velocity after the collision.

What is the maximum acceleration with which a person can climb a rope if the rope can bear a maximum tension equal to 2/3 of his weight?

State and prove the work-energy theorem.

A spring of spring constant 1000 N/m is compressed by 10 cm. Find the elastic potential energy stored and the velocity of a 0.5 kg block when the spring is released.

Distinguish between elastic and inelastic collisions. Give one example of each.

An engine pumps 500 kg of water per minute to a height of 10 m. Find the power of the engine. (g = 10 m/s²)

Show that in an elastic head-on collision, two equal masses exchange velocities.

State and prove the theorem of parallel axes for moment of inertia.

A solid sphere and a hollow sphere of the same mass and radius roll down an inclined plane without slipping. Which reaches the bottom first and why?

Derive an expression for the kinetic energy of a rolling body.

Find the moment of inertia of a thin uniform rod of mass M and length L about an axis through one end perpendicular to the rod.

A diver pulls in her arms while performing a somersault. Explain using the law of conservation of angular momentum why her rate of rotation increases.

Derive an expression for the orbital velocity of a satellite. What is the orbital velocity for a satellite close to the Earth's surface? (g = 9.8 m/s², R = 6400 km)

State Kepler's laws of planetary motion. Derive Kepler's Third Law using Newton's law of gravitation.

How does acceleration due to gravity vary with (i) altitude and (ii) depth below the Earth's surface?

Calculate the escape velocity from the surface of the Earth. (g = 9.8 m/s², R = 6.4 × 10⁶ m)

What is a geostationary satellite? State two conditions for a satellite to be geostationary.

Define Young's modulus, Bulk modulus, and Shear modulus. In which situation is each relevant?

A wire of length 2 m and cross-sectional area 10⁻⁶ m² is stretched by 1 mm under a force of 200 N. Find Young's modulus of the material.

Draw and explain the stress-strain curve for a ductile material. Mark all important points.

What is elastic fatigue? How does it affect the choice of materials in engineering?

Why are girders used in construction made in the I-shape cross-section?

State and derive Bernoulli's theorem. List two applications of Bernoulli's principle.

A raindrop of radius 1 mm falls with terminal velocity 5 m/s. Find the coefficient of viscosity of air. (ρ_water = 10³ kg/m³, ρ_air ≈ 0)

Prove that the excess pressure inside a soap bubble is 4T/r.

Water flows through a pipe of diameter 4 cm at 2 m/s. It narrows to 2 cm diameter. Find the velocity in the narrower section.

State Archimedes' principle. A solid of mass 500 g has an apparent weight of 4.5 N when fully submerged in water. Find its volume. (g = 10 m/s²)

A steel rod of length 1 m is heated from 20°C to 120°C. Find the increase in length. (α_steel = 1.2 × 10⁻⁵ /°C)

State Newton's law of cooling. A body cools from 80°C to 60°C in 5 minutes. How long will it take to cool from 60°C to 40°C in a room at 20°C?

Distinguish between conduction, convection, and radiation. Give two examples of each.

Define specific heat capacity and latent heat. 200 g of water at 80°C is mixed with 100 g of water at 20°C. Find the final temperature.

What is the anomalous expansion of water? What is its significance in nature?

State the first law of thermodynamics. Apply it to (i) isothermal and (ii) adiabatic processes.

Describe the Carnot cycle. Derive an expression for the efficiency of a Carnot engine.

State the second law of thermodynamics in two different ways. Show that they are equivalent.

A Carnot engine operates between 727°C and 27°C. Find its efficiency and the heat rejected to the sink for every 1000 J of heat absorbed.

What is the coefficient of performance (COP) of a refrigerator? How is it related to the efficiency of a heat engine?

Derive an expression for the pressure exerted by an ideal gas using kinetic theory. Hence obtain the kinetic interpretation of temperature.

State the law of equipartition of energy. Using it, find C_v and C_p for a diatomic gas and calculate γ.

Calculate the rms speed of nitrogen molecules at 27°C. (M = 28 g/mol, R = 8.31 J mol⁻¹ K⁻¹)

What is mean free path? On what factors does it depend?

At what temperature will the rms speed of oxygen molecules be equal to the rms speed of hydrogen molecules at 300 K?

Derive expressions for displacement, velocity, and acceleration of a particle in SHM. Show that acceleration is proportional to displacement and directed towards the mean position.

Show that total energy of a particle in SHM is constant. How does it vary with displacement?

Find the period of a spring-mass system with spring constant 200 N/m and mass 0.5 kg.

What is resonance? Give two examples of resonance — one beneficial and one harmful.

The time period of a simple pendulum is 2 s on Earth's surface. What will be its period on a planet where g is half of Earth's g?

Derive Newton's formula for speed of sound in a gas. What correction did Laplace make and why?

Explain the formation of standing waves. Derive the frequencies of normal modes for a string fixed at both ends.

State the Doppler effect. Derive the general formula for apparent frequency when both source and observer are moving.

Two sound waves of frequencies 512 Hz and 516 Hz are superimposed. Find the beat frequency.

A string of length 0.5 m and linear mass density 10⁻³ kg/m is under tension 8 N. Find the fundamental frequency.