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Accuracy

When a measured value is close to the accepted value.

Standard metric units for mass, time, and length

Mass: kilogram (kg); Time: second (s); Length: meter (m).

Weight

The Earth's gravitational force on an object.

Mass and weight location effect

Mass does not change (independent of location); weight decreases with greater distance from the planet.

Gravitational force indication

If the object is on or near Earth (or another large planet or moon).

Inertia

The tendency of an object to maintain constant velocity (magnitude and direction).

Distance travelled

The length of the path taken by a moving object.

Mass and weight relationship

Weight = Mass × Gravitational acceleration (9.8 m/s² on Earth).

Free-body diagram

A visual model showing all external forces acting on an object, represented by labeled arrows.

Acceleration

The rate of change of an object's velocity.

Vector quantities

Displacement, velocity, acceleration, force.

Horizontal velocity of a projectile

It remains constant, as there are no horizontal forces.

Mass and inertia relationship

Mass measures an object's resistance to changes in velocity (inertia).

Average velocity calculation

Total displacement divided by total time.

Tension force indication

If it is being pulled by a rope, string, cable, wire, or similar object.

Freefall

A condition where the only significant external force is gravity.

Acceleration of a horizontally launched projectile

It is constant at 9.8 m/s² downwards due to gravity.

Newton's First Law

An object will maintain a constant velocity unless acted upon by an unbalanced force.

Newton's Second Law

Acceleration is directly proportional to net force and inversely proportional to mass.

Newton's Third Law

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

Equilibrium

A situation where all external forces are balanced; net force = 0.

Velocity

The rate of change of position, including speed and direction.

Mass effect on fall time

Freefall acceleration is independent of mass.

Gravitational force distance effect

It decreases proportionally to the square of the distance.

Momentum and impulse

Momentum: mass × velocity. Impulse: force × time.

Momentum and impulse relationship

Impulse equals the change in momentum.

Conservation of momentum

Total momentum in a system remains constant.

Coefficient of friction

The ratio of friction force to normal force; depends on surface characteristics.

Padding or cushioning injury prevention

It increases interaction time, reducing force for the same impulse.

Scalar quantities

Distance, speed, mass, time.

Precision

When multiple measurements have similar values.

Displacement

The straight-line distance between initial and final positions, including direction.