# Important Physics Formulas for ICSE Class 9

In this mini-blog, we have listed all the important physics formulas for ICSE class 9 examination.

ICSE(Indian Certificate of Secondary Education) is one of the toughest boards in India. Due to its vast syllabus, most students fail to cope with it and end up scoring low marks in the examination.

Physics is a very important and mind-itching subject for ICSE class 9 students. In the final examination, students have to deal with both theoretical and practical sections.

In ICSE or even other boards, an elementary understanding of Physics is necessary to decode the chapter in successive classes. It is very necessary to retain the formula to solve numerical problems in the physics section.

Jotting down all the important formulas is very important during question practice. It will help you to retain the formula for a very long time.

To make your work easy, we have provided you with all the important Physics formulas for ICSE class 9.

## Force and Motion

Read all the important formulas of chapter force and laws of motion class 9 discussed below.

• Average Speed

The average speed is the ratio of the total distance to the total time.

Average speed = Total DistanceTotal Time

• Velocity

Velocity is the ratio of displacement to time. It is denoted by v. Read velocity formula class 9 to know more about velocity.

V = st

Where

v = velocity

s = displacement

t = time

• Acceleration

The ratio of the difference between final velocity and initial velocity to time. It is denoted by a.

a = v-ut

Where,

a = acceleration

v = final velocity

u = initial velocity

t = time

### Newton’s first law of motion

Newton’s first law of motion also known as the law of inertia states that its body at rest or moving will remain at rest or moving until an external force is applied to it.

For more read force and laws of motion for class 9.

### Newton’s second law of motion

Newton’s second equation of motion for class 9 states that the rate of change in momentum due to acceleration is equal to force acting upon it.

F = ma

Where,

F = force acting upon the object.

m = mass of the body.

a = acceleration of the body.

### Momentum

Momentum is a product of mass and velocity. It is denoted by p.

p = mv

Where,

p = momentum

m = mass of an object

v = velocity of the object

### Kinetic Energy

The energy associated with the movement of the objects is called kinetic energy. It is denoted by Ek

Ek = 1/2mv2

Where,

Ek = Kinetic energy

m  = mass of an object
v  = velocity of an object

### Gravitational potential energy

Ep = mgh

Ep = Gravitational Potential energy

m  = mass of an object

g = gravitational acceleration

h  = height

### Power

Total work done per unit time is defined as power. It is denoted by P.

P  = WT

P  = ET

Where,

P = Power

W= total work done

T = time

Efficiency

Efficiency = power output power Input 100%

### Hooke’s Law

F = kx

F = Force

k = spring constant

x = compression of spring

### Force and Pressure

• Density

The density is defined as the mass per unit volume.  It is denoted ρ.

ρ =  mv

Where,

ρ = density

m = mass of an object

v = velocity of an object

• Pressure

The force acting upon per unit area is pressure. It is denoted P.

P = FA

Where,

P = Pressure

F = Force acting upon it.

A = Area

• Liquid Pressure

P = hρg

Where,

P = Liquid Pressure

h = depth or height

ρ = density

g = gravitational field strength

• Pressure in liquid

P = Patm + hρg
Where,

P = Pressure in liquid

Patm= atmospheric pressure

h = depth or height

ρ = density

g = gravitational field strength

Q1. What is the SI unit of energy?

Ans- The SI unit of energy is Joule. It is denoted by J.

Q2. What is the current formula?

Ans- According to ohm’s law, the voltage in the circuit is directly proportional to the current flowing in the circuit.

V ∝ I

V = IR,

Where R is resistance constant.

From we can derive the current formula,

I = V/R