Physics Formula for Class 9
Suppose three objects begin walking down a field of smooth, freshly fallen snow. Before anything begins, they begin to move in and out of range of each other. Imagine that we have a simple, yet fullscale version of this situation with coordinates for the movement of the objects: However, our situation is much more complex, and actually consists of many different trajectories:
L! E! H! What if we had to accept a different realization of this situation?
Suppose that we know at least one kind of motion, and maybe some other kinds that seem to be similar in movement. This generalized representation of the situation would not have enough variety to make it a threedimensional space, so it could not be considered real.
Also Read: Physics Formula for Class 10
In order to create the state we want with this generalized representation, we must leave open the door to some additional, far more complex eventual state (e.g., change from one direction to another), which is what the threedimensional space is. Moreover, we might want to incorporate up to three different kinds of horizons, which as we could only imagine sounds like crazy, but by changing its direction from the origin, the larger distances go from between two points, which corresponds to changes in our longrange light.
The result would be much more complicated than the classic version of the situation that we took before.
Relative Deviation
Relative Deviation = Means Deviation/ Mean Value × 100
Prefixes:
Prefixes

Value

Standard form

Symbol

Tera

1000000000000

10¹²

T

Giga

1000000000

10⁹

G

Mega

1000000

10⁶

M

Kilo

1000

10³

k

deci

0.1

10^{1}

d

centi

0.01

10^{2}

c

milli

0.001

10^{3}

m

micro

0.000001

10^{6}

μ

nano

0.000000001

10^{9}

n

pico

0.000000000001

10^{12}

p

Units for Area and Volume
1m² = 10⁴ cm² (10,000cm²) 1cm² = 104 m² (1/10,000 m²)
1m³ = 10⁶ cm³ (1,000,000cm³) 1cm³ = 106 m³ (1/1,000,000m³)
Force and motion
Average Speed :
Average Speed = Total Distance/ Total Time
Velocity :
V = s/t
V = Velocity (ms1)
s = displacement (m)
t = time (s)
Acceleration :
a = v – u / t
a = acceleration (ms2)
v = final velocity (ms1)
u = initial velocity (ms1)
t = time for the velocity change
(s)
Momentum
p = m × v
p = momentum (kg ms1)
m = mass (kg)
v = velocity (ms1)
m₁u₁ + m2u2 = m1v1 + m2v2
m₁ = mass of object 1
m₂ = mass of object 2
u₁ = initial velocity of object 1
u₂ = initial velocity of object 2
v₁ = final velocity of object 1
v₂ = final velocity of object 2
Energy
Kinetic Energy :
E_{k} = 1/2 mv²
E_{k} = Kinetic Energy (J)
m = mass (m)
v = velocity (ms1)
Gravitational Potential Energy :
E_{p} = Potential Energy (J)
m = mass (m)
g = gravitational acceleration (ms2)
Elastic Potential Energy :
E_{p }= ½ kx²
E_{p }=Potential Energy (J)
k = spring constant
x = extension of spring (m)
E_{p} = ½ Fx
F = Force (N)
Power and Efficiency
Power :
P = W/t
P = E/t
P = power (W)
W = work done (J or Nm)
E = energy change
t = time (s)
Efficiency :
Efficiency = Useful Energy/ Energy x 100%
Or
Efficiency = Power Output/Power Input x 100%
Hooke’s Law
F = kx
F = Force (N)
k = spring constant (Nm^{1})
x = extension or compression of spring (m)
Force and Pressure
ρ = m/v
ρ = density (kg m^{3})
m = mass (kg)
v = volume (m)
Pressure :
P = F/A
P = Pressure (Pa or N m^{2})
F = Force acting normally to the surface (N)
A = Area of the surface (m^{2})
Liquid Pressure :
h = depth (m)
ρ = density (kg m^{3})
g = gravitational Field Strength (N kg^{1})
Pressure in Liquid :
P = P_{atm }+ hρg
h = depth (m)
ρ = density (kg m^{3})
g = gravitational Field Strength (N kg^{1})
P_{atm }= atmospheric Pressure (Pa or N m^{2})