# Download the free Pdf sheet of list of physics formulas class 11 for IIT JEE & NEET For chapter-Fluid mechanics

#### Physics Formulas

Fluid is the name given to a substance, which begins to flow when an external force is applied to it.

## Fluids exert thrust

This normal change in momentum transferred to the walls per unit of time by the molecules of fluid accounts for the normal force or thrust of fluid on the walls of the container.

### Liquid

The normal force 9or thrust) exerted by a liquid at rest per unit area of the surface in contact with their its called pressure of liquid or hydrostatic pressure.

### Density and relative density

Density of a substance is defined as the mass per unit volume of the substance i.e.,

Relative density of substance is defined as the ratio of its density to the density of water at 4°C,

### Variation of pressure with depth:

The pressure is same at all points inside the liquid lying at the same depth in a horizontal plane. P – Pa = hρg. It is called gauge pressure Gauge pressure at a point in a liquid is the difference of total pressure at the point and atmospheric pressure. Pressure exerted by a liquid column of height h is independent of area of cross-section A but depends upon the height h of the liquid coloumn and density ρ of the liquid.

### Pascal’s law

It states that if the gravity effect is neglected, the pressure at every point of liquid in equilibrium of rest is same. Principle of transmission of pressure in liquids or gases. Pascal’s law states that the increase in pressure at one point of the enclosed liquids in equilibrium of rest is transmitted equally to all other points of the liquid and also to the walls of the container, provided the effect of gravity is neglected.

### Atmospheric pressure

The gaseous envelope surrounding the earth is called earth’s atmosphere. The atmospheric pressure at any point is equal to the weight of a vertical coloumn of air of unit cross-sectional area extending from that point to the top of the earth’s atmosphere.

#### Buoyancy

This upward force acting on the body immersed in a fluid is called upward thrust or buoyant force or simply buoyancy.

### Archimede’s Principle

It states that when a body is immersed wholly or partly in a liquid at rest, it loses some o its weight. The loss is weight of the body in the liquids is equal to the weight off the liquid displaced by the immersed part of the body.

### Law of Floatation

When a body of density ρ, volume V is immersed completely in a liquid of density σ, two forces are acting on it.

• Case I- If W > w, then W – w is positive. In this case, the body will sink to the bottom of the liquid. If the body is not hollow from inside, then the density of solid body is greater than the density of liquid (i.e. ρ > σ).
• Case II- If W < w, then W – w is negative. In this case, the body will rise above the surface of liquid to such an extent that the weight of the liquid displaced by the immersed part of the body.
• Case III- If W = w, then W – w = 0. It means the resultant force acting on the boy fully immersed in the lucid is zero. In this case the body is at rest anywhere within the liquid. The apparent weight of the body is zero at all positions inside the liquid. In this situation, the body will flaot if its whole volume is just immersed in the liquid. If the is solid then the density of body is equal to the density of liquid i.e., ρ = σ )

Do follow NCERT Solutions for class 11 Physics prepared by Physics Wallah. If any students need to take the online test to check their concepts or undertstanding then they can visit Quiz for Fluid Mechanics.

Download the Pdf of class 11 physics formula sheet of chapter Fluid mechanics from the link given below