form 4 physics formula list

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Physics Formula List: Form 4

Form 4 Equations/Uses

Chapter 1:

Introduction to

Physics

Equation to determine the consistency of measurements: relative deviation

Relative deviation =valueaverage

deviationaveragex 100%

Equation to determine period of oscillation of a simple pendulum system

T= 2g

lT= period (s)

l= length of pendulum bob (m)

g= gravitational field strength (10ms-2)

Equation to determine the gradient of a graph

Chapter 2:

Forces andMotion

Equation to determine speed

Speed = Distance travelledTime taken

Equation to determine average speed

Average speed = Total distance travelled

Total time taken

Equation to determine velocity

Velocity = DisplacementTime taken

Equation to determine average velocityAverage velocity = Total Displacement

Total time taken

Gradient, m =x

y

y = change iny

x = change inx
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Equation to determine acceleration

Acceleration, a=t

uv v= final velocity (ms

-1)

u= initial velocity (ms-1

)

t= time (s)

Equations to solve the problems involving motion with constant velocity and

motion with constant acceleration

Motion with constant velocity Motion with constant acceleration

s = (2

vu ) x t

v = u+ at

s = ut +2

1at

2

s = vavx t

v2= u

2+ 2as

Equation to determine momentum of an object

p= mx v p= momentum (kgms-1)m = mass (kg)

v = velocity (ms-1

)

Equation to solve the problems involving elastic collisionm1u1+ m2u2 = m1v1+ m2v2

Equation to solve the problems involving inelastic collision

m1u1+ m2u2 = (m1+ m2) v

Equation to solve the problems involving explosion

m1v1 + m2v2 = 0

Equation to determine resultant force

F= ma F= Force (N)

m= mass (kg)

a= acceleration (ms-2

)

Equations to determine impulseImpulse = FtImpulse = mvmu m= mass (kg)


)

v = final velocity (ms-1

)

Equation to determine impulsive force

F=t

mumv F= impulsive force (N)

m = mass (kg)


)

v = final velocity (ms-1)


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t= time of impact (s)

Equation to determine Weight

W= mg W= weight (N)

m = mass (kg)

g= 10 ms-2

Equations to determine Weight in lift

Situation Explanation

(a)Lift at restor moves up or

down at a constant

velocity.

Weight, W = mg

(b) Lift moves up with an

accelerationofa ms-2

.

Weight, W=m(g+a)

(c)Lift moves down with an

accelerationofa ms-2.

Weight, W=m(g-a)


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Equation to calculate workW= Fs W= Work (J)

F = Force (N)

s = displacement (m)

Equation to calculate gravitational potential energyEp= mgh E p= gravitational potential energy (J)

m= mass of af bject (kg)

g= 10 ms-2

h= height of object (m)

Equation to calculate kinetic energyEk= mv

2Ek= kinetic energy (J)

m= mass of af bject (kg)

v= velocity (ms-1

)

Equation to calculate power

P =t

WP= Power of a device (W)

W= work (J)

T= time to do work (s)

Equations to calculate efficiency

EfficiencyInputEnergy

OutputEnergyUsefulx100%

Efficiency InputPower

OutputPowerUseful

x100%

Equationto solve the problems involving spring (Hookes Law)

F=kx F= Force (N)

k=spring constant (Nm-1

)

x= extension/compression of a spring (m)


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Equations to determine the elastic potential energy stored in a spring

Ep= Fx Ep= elastic potential energy stored in a spring (J)

Ep= kx2

F= Force (N)

x= extension/compression of a spring (m)

k=spring constant (Nm-1

)

Chapter 3:

Forces andPressure

Equation to calculate pressure

P=AF P= Pressure (Pa)

F= Force (N)

A= Area of contact (m2)

Equation to calculate pressure in liquid

P = hg P = Pressure in liquid (Pa)

h= depth of liquid (m)

= density of liquid (kgm-3

)

g= 10 ms-2

Equation to solve the problems involving Pascals Principle

1

1

A

F=

2

2

A

FF1= input force (N)

F2 = output force (N)

A1= input piston area (m2)

A2 = output piston area (m2)

Equation to determine buoyant forceBuoyant force =Vg = density of fluid displaced (kgm

-3)

V= Volume of fluid displaced (m3)

g= 10 ms-2

Chapter 4: Heat Equation to solve the problem involving calibration of a thermometer

=0100

0

ll

ll

x1000C = temperature (

0C)

l0 = length of mercury thread at 00C (cm)

l100 = length of mercury thread at 1000C (cm)

l=length of mercury thread at 0

C (cm)

Equations to solve the problems involving specific heat capacity

Q= mc Q= heat absorbed/released (J)

m= mass of object (kg)c = specific heat capacity of an object (Jkg

-10C

-1)

= change in temperature (0C)

Pt= mc P = Power of heater (W)

t= time of heating (s)


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Equations to solve the problems involving specific latent heat

Q= mlf Q= heat absorbed/released (J)

m= mass of object (kg)

lf= specific latent heat of fusion (Jkg-1

)

Q= mlv lv = specific latent heat of vapourization (Jkg-1

)

Equation to solve the problems involving Boyles LawP1Vl = P2V2 P1 = Initial pressure of gas (Pa)

P2 = Final pressure of gas (Pa)

V1 = Initial volume of gas (m3)

V2 = Final volume of gas (m3)

Equation to solve the problems involving Charles Law

1

1

T

V =2

2

T

V V1 = Initial volume of gas (m3)

V2 = Final volume of gas (m3)

T1 = Initial temperature of gas (K)

T2 = Final temperature of gas (K)

Equation to solve the problems involving Pressure Law

1

1

T

P=

2

2

T

PP1= Initial pressure of gas (Pa)

P2 = Final pressure of gas (Pa)

T1 = Initial temperature of gas (K)

T2 = Final temperature of gas (K)

Equation to convert temperature Celcius from to Kelvin

T= + 273 T= temperature (K)

= temperature (0C)

Chapter 5:

LightEquations to determine refractive index of a transparent medium

n=r

i

sin

sinn= refractive index (no unit)

i= angle of incidence (0)r= angle of refraction (0)

n =v

cc= speed of light in vacuum (3x10

8ms

-1)

v= speed of light in the medium (ms-1)

n =d

DD= real depth of object (m)

d= apparent depth of image (m)

n =csin

1 c = critical angle of the transparent medium (0)


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Equations to determine the power of lenses

P=f

1 P= power of lens (D)

f= Focal length of a lens (m)

Equations to solve the problems involving lenses

u

1

+ v

1

= f

1

f= Focal length of a lens (m)

u= object distance (m)

v= image distance (m)

m =u

v m = linear magnification of a lens (no unit)

u= object distance (m)

v= image distance (m)

form 4 physics formula list

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