ncert solutions physics class 11th

In a sample, Root mean square (RMS) speed refers to the average of the squares of the speeds of all gas molecules. It helps in measuring the gas particles' speed and takes into account the kinetic energy. Mathematically, it is expressed as:

Here, T is the temperature in Kelvin, k is the Boltzmann constant, and m is the mass of one molecule. M is the molar mass and R is the universal gas constant. The RMS speed is calculated by kinetic theory using the relationship between molecular motion, kinetic energy and pressure. RMS speed shows with which speed the molecules are moving in a gas sample and increases with temperature.

Escape velocity is the least velocity an object needs without any further propulsion to escape the Earth's gravitational field. The escape velocity for the earth is nearly 11.2 km/s. It is derived by using the conservation of energy principle that says for an object to move to an infinite distance, its kinetic energy should be equal to the gravitational potential energy.

When there is no normal force acting on a body, weightlessness is experienced, and the body free fall under gravity. The concept of gravity is still acting on the body, however, there is no weight sensation of any reaction force from any surface or ground. The weightlessness felt by the astronauts in an orbiting spacecraft is not because gravity is not present but because while they are moving forward, both, they and the spacecraft are in continuous free fall towards the Earth. The role of the normal force in defining weight can be understood from this phenomenon also how it is different from the actual gravitational force.

The gravitational pull of the Moon is the main reason behind the tides of Earth and it is less dependent on the sun. The gravitational pull of the moon on Earth is stronger than the sun's gravitational pull due to Earth's proximity to the moon. The Earth's oceans get pulled by the moon's gravity, which creates a bulge of water on the side of the Earth facing the moon. Also, another bulge gets created on the opposite side due to the water's inertia. When the earth rotates, its areas pass through these bulges which form the high and low tides. Each day, two high and two low tides are created by the gravitational interaction.

To get the best results, students should begin their preparation by reading the NCERT chapter thoroughly, especially dimensional analysis, numerical problems involving significant figures, and errors. They need to practice questions first by not looking at the answers and after they complete their solutions, they can cross-check with the solutions given here, they need to make a list of formulas and units to revise regularly. Also, they should refer to other reference books for better practice.