Class 11 Physics NCERT

Some of the common systems of units that are used in physics are: CGS system, FPS system, MKS system, and SI system.

A body is said to be in motion if it changes its position with respect to time.

Motion in a plane is the motion in two dimensions, for instance, projectile motion, circular motion and so on.

The property of an object by virtue of which it cannot change its state of uniform motion along a straight line or rest on its own is called as inertia. It is the measure of the mass of a body.

Work is the measurement of energy transfer that takes place when an object is displaced by an external force applied in the direction of the displacement.

Imagine a rectangular block placed on the slanting edge of a right-angled triangle. If the block is assumed to slide down this edge without any side movement, every point in the rectangular block experiences the same displacement and more importantly, the distance between the points is also maintained.

Gravitation or gravity is a naturally occurring phenomenon or a force which exists among all material objects in the universe.

What happens to a rubber band when you stretch it and let go? It deforms but regains its original nature when you stop applying a force. But say, you take an aluminium rod and try to bend it using your arm strength. You somehow do manage to bend it a little and then stop applying force. Does the rod regain its original shape? Of course not.

Fluids are the substances which move or flow in a certain direction when an external force is applied to them. Fluids can be either gases or liquids. However, when you study fluids and their mechanical properties, you come across two topics namely hydrodynamics and hydrostatics.

By definition, matter or material is anything that has mass and occupies space. Everything we see around us is matter. For example, a water bottle is made up of plastic or any metal, both of which are examples of matter.

Thermodynamics is concerned with the relationship between other forms of energy and heat. It explains how thermal energy is converted from other forms of energy. The energy coming from heat is termed thermal energy. When the tiny particles within an object move, they generate heat, more amount of heat is generated, when these particles move at a faster pace.

The kinetic theory of gases explains the behavior of molecules, which should further explain the behavior of an ideal gas. Ideal Gas equation consists of the pressure (P), volume (V), and temperature (T) of gases at low temperature and the equation is: PV = nRT.

Oscillation is a measure of some repetitive variation, as a function of time. It can be measured with respect to a state of equilibrium. The most common and simplest example for oscillation is the motion of a simple pendulum.

There are four types of waves - mechanical, transverse, longitudinal, progressive.