Understanding Scalar and Vector Quantities in Physics

Scalar quantity

A quantity with only magnitude (size).

Vector quantity

A quantity with both magnitude and direction.

Displacement

Distance in a specific direction.

Velocity

Speed in a specific direction.

Contact force

A force that acts when objects are touching.

Non-contact force

A force that acts without objects touching, e.g., gravity.

Terminal velocity

The maximum steady velocity an object can reach when falling.

Closed system

A system where no external forces act, so no energy is lost.

W ∝ m

Weight is directly proportional to mass.

Weight formula

W = m · g, where W is weight, m is mass, and g is gravitational field strength.

Elastic deformation

When an object returns to its original shape after a force is removed.

Inelastic deformation

When an object does not return to its original shape after a force is removed.

Hooke's Law

Extension is proportional to force until the elastic limit is reached.

Elastic limit

The point beyond which an object is inelastically deformed, and the force-extension graph is no longer linear.

Force formula using Hooke's Law

F = k · e, where F is force, k is spring constant, and e is extension.

Center of mass

The point where the weight of an object is concentrated.

Work done

The energy transferred when a force moves an object over a distance.

Work done formula

W = F · s, where W is work done, F is force, and s is distance.

Newton's First Law

An object remains at rest or in uniform motion unless acted on by a resultant force.

Newton's Second Law

Acceleration is proportional to force and inversely proportional to mass (F = ma).

Newton's Third Law

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

Inertia

The tendency of an object to resist changes in its motion.

Inertial mass

A measure of how difficult it is to change the velocity of an object (m = F / a).

Stopping distance

The total distance needed to stop a vehicle, including thinking and braking distance.

Thinking distance factors

Tiredness, distractions, alcohol, and drugs.

Braking distance factors

Wet roads, worn brakes, increased speed, and greater mass.

Momentum

The product of mass and velocity (p = m · v).

Principle of conservation of momentum

Total momentum before an event equals total momentum after if no external forces act.

Acceleration

The rate of change of velocity.

Acceleration formula

a = Δv / t, where Δv is change in velocity, t is time.

Gradient on a distance-time graph

Speed.

Area under a velocity-time graph

Distance traveled.

Drag

A resistive force opposing motion through a fluid.

Elastic potential energy formula

E_e = 0.5 · k · e^2, where k is spring constant, e is extension.

Skid cause

A braking force greater than friction between the tires and the road.

Braking distance increase

Braking distance quadruples when speed doubles because kinetic energy increases with the square of speed.

Relationship between speed and thinking distance

Thinking distance is directly proportional to speed.

Gravitational field strength on Earth

Approximately 9.8 N/kg.

Parachute effect

It increases air resistance, making it greater than the skydiver's weight.

Deceleration

Negative acceleration or slowing down.