Physics is the branch of science that deals with the study of matter, energy, and their interactions. It attempts to explain natural phenomena using mathematical relationships and experimental verification.
Physical quantities that cannot be derived from other quantities are called base quantities. The seven base quantities in SI system are:
Quantities that are derived from base quantities are called derived quantities. Examples:
An object is said to be at rest if it does not change its position with respect to its surroundings with time. An object is said to be in motion if it changes its position with respect to its surroundings with time.
Speed = Distance / TimeVelocity = Displacement / Time
Speed is a scalar quantity (only magnitude).
Velocity is a vector quantity (magnitude + direction).
Acceleration = Change in Velocity / Timea = (v - u) / tv = u + ats = ut + ½at²v² = u² + 2as
"A body at rest remains at rest and a body in motion continues in motion with constant velocity unless an external force acts on it."
F = maNewton (N) is the SI unit of force. 1 N = 1 kg m/s²
"For every action, there is an equal and opposite reaction."
The force that opposes the motion between two surfaces in contact is called friction.
f = μNThe turning effect of a force is called moment of force or torque.
Torque = Force × Perpendicular Distanceτ = F × d"For a body in equilibrium, the sum of clockwise moments equals the sum of anticlockwise moments."
The point at which the entire mass of the body appears to be concentrated is called center of mass.
A body is in equilibrium if:
"Every particle in the universe attracts every other particle with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them."
F = G(m₁m₂)/r²Weight = Mass × Gravitational AccelerationW = mg
v = √(GM/r)v = √(2GM/r)Work = Force × DisplacementW = F × d × cosθThe capacity to do work is called energy.
KE = ½mv²
PE = mgh
"Energy cannot be created or destroyed, but can be converted from one form to another."
Power = Work / TimeP = W/tDensity = Mass / Volumeρ = m/VPressure = Force / AreaP = F/AP = ρgh"A body immersed in a fluid experiences an upward force equal to the weight of the fluid displaced by it."
Stress = Force / AreaStrain = Change in Length / Original LengthHooke's Law: Stress ∝ Strain
Heat is the form of energy transferred due to temperature difference.
Temperature is the degree of hotness or coldness of a body.
Q = mcΔTHeat required to change state without temperature change:
Q = mL