A - Space, time and motion (Without Galilean and special relativity)

Acceleration (a)

the rate of change of velocity. (if constant: a=Δv/Δt)

Air drag

resistive force that acts on objects moving through air.

Angular acceleration (α)

the rate of change of angular velocity. (α=Δω/Δt, α=a/r)

Angular displacement (θ)

the angle through which an object moves on a circular path.

Angular impulse (ΔL)

the change in angular momentum of a rigid body due to the application of torque over a period of time. (ΔL=τΔt)

Angular momentum (L)

the rotational equivalent of linear momentum, the product of its moment of inertia and its angular velocity. (L=Iω, L=rp)

Angular velocity (ω)

the rate of change of angular displacement.(ω=Δθ/Δt)

Average speed (v)

the total distance traveled divided by the total time taken. (scalar) (v=s/t)

Average velocity (v)

the total displacement divided by the total time taken (vector) (v=s/t)

Centripetal force

force that acts on a body moving in a circular path and is directed towards the centre around which the body is moving.

Collisions

are interactions where two or more objects exert forces on each other for a short time.

Conservation of angular momentum

Angular momentum (L) is conserved unless an external torque acts on the system.

Conservation of mechanical energy

In an isolated system, the total mechanical energy is conserved:

(Etotal=Ek+Ep=constant)

Contact forces

forces that arise due to direct physical interaction between two objects.

Density

how much mass is contained in a given volume of the medium. (d=m/V)

Drag force

resistive force that acts opposite to the direction of an object’s motion through a fluid (such as air or water)

Efficiency

how effectively a system converts input energy into useful output energy./(of a heat engine) measures how effectively it converts input energy into useful work.

Elastic collision

both momentum and kinetic energy are conserved.

Elasticity

describes how easily a medium returns to its original shape after being disturbed.

Friction force

a force that opposes the motion of an object.

Impulse (Δp)

describes how a force applied over a period of time changes an object's momentum. (Δp=FΔt)

Impulse-momentum theorem

the impulse on an object is equal to the change in its momentum

Inelastic collision

momentum is conserved, but kinetic energy is not.

Inertia

the tendency of an object to resist changes in its state of motion

Inertial reference frame

Newton’s first law holds true: an object at rest stays at rest, and an object in motion continues in a straight line at constant speed unless acted upon by a force

Instantaneous acceleration

the acceleration at a specific moment in time. (suvat)

Kinetic energy (Ek)

the energy an object possesses due to its motion. (Ek=mv²/2)

Mechanical energy (Em)

is the sum of an object's kinetic energy and potential energy.

Momentum (p)

a measure of how difficult it is to stop a moving object. It depends on two factors: the object's mass and its velocity. (p=mv)

Newton's first law of motion

An object at rest stays at rest, and an object in motion stays in motion at a constant velocity, unless acted upon by a net external force.

Newton's second law of motion

The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. (a=F/m)

Newton's third law of motion

For every action, there is an equal and opposite reaction.

Perfectly inelastic collision

the colliding objects stick together and move as one mass after the collision.

Potential energy (Ep)

the energy stored in an object due to its position or configuration. (Ep=mgh)

Power (P)

the rate at which energy is transferred or converted (P=ΔE/t)

Projectile motion

the motion of an object thrown or projected into the air, subject to only the acceleration of gravity.

Rigid body

an idealized object in which the relative positions of all particles remain fixed, regardless of external forces or torques.

Rotational equilibrium

defined as the state of movement where angular acceleration is zero: total torque is zero.

Rotational kinetic energy/angular kinetic energy

kinetic energy due to the rotation of an object and is part of its total kinetic energy.

Scalar quantities

have only magnitude and no direction.

Terminal velocity

the constant speed an object reaches when the drag force equals the gravitational force acting on it.

The law of conservation of momentum

the total momentum of an isolated system remains constant if no external forces act on it.

The work-energy theorem

the net work done on an object is equal to the change in its kinetic energy. (W= ΔEk)

Torque (τ)

rotational equivalent of force. It measures the ability of a force to cause an object to rotate. (τ=rFsinθ)

Vector quantities

have both magnitude and direction.

Work (W)

the product of the force applied to an object, the displacement of the object, and the cosine of the angle between the force and the displacement. (W=Fscosθ)