Movement and Interactions

Distance

Distance

The total path traveled by an object, regardless of direction.

Displacement

The shortest path between the initial and final position of an object, considering direction.

Example of Displacement

Walking 3 meters east, then 4 meters north results in a displacement of 5 meters northeast.

Speed

The rate at which an object covers distance, specifically the rate of change of an object’s distance (scalar quantity).

Velocity

The rate at which an object changes its position, specifically the rate of change of an object’s displacement (vector quantity).

Example of Velocity

A car traveling 60 km/h north has a speed of 60 km/h and a velocity of 60 km/h north.

Acceleration

The rate of change of velocity.

Example of Acceleration

A car increasing its velocity from 0 to 20 m/s in 4 seconds has an acceleration of 5 m/s².

Distance-Time Graphs

Slope represents speed. A straight line indicates constant speed. A curve indicates changing speed.

Example of Distance-Time Graph

A distance-time graph showing a straight line indicates the object is moving at a constant speed.

Velocity-Time Graphs

Slope represents acceleration. Area under the graph represents displacement.

Example of Velocity-Time Graph

A velocity-time graph with a slope of zero indicates constant velocity.

Example of Equations of Motion

A car starting from rest (u=0) and accelerating at 3 m/s² for 5 seconds travels 37.5 meters.

Centripetal Force

Force directed towards the center of a circular path.

Example of Centripetal Force

The tension in a string when swinging a ball around in a circle provides the centripetal force.

Centripetal Acceleration

Acceleration directed towards the center of a circular path.

Example of Centripetal Acceleration

A car turning in a circular path experiences centripetal acceleration.

Friction

The force that opposes the motion of objects.

Example of Friction

Rubbing hands together generates heat due to friction.

Tension

The force exerted by a stretched object like a rope or cable.

Example of Tension

The tension in a rope when pulling a sled.

Normal Force

The support force exerted upon an object in contact with another stable object.

Example of Normal Force

A book resting on a table experiences a normal force from the table.

Gravitational Force

The force of attraction between two masses.

Example of Gravitational Force

The Earth's gravitational pull on a falling apple.

Electrostatic Force

The force between charged objects.

Example of Electrostatic Force

The repulsion between two positively charged balloons.

Magnetic Force

The force between magnets or magnetic materials.

Example of Magnetic Force

The attraction between a magnet and a refrigerator door.

Newton's First Law

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

Example of Newton's First Law

A book remains on a table until pushed.

Newton's Second Law

The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.

Example of Newton's Second Law

Pushing a car with a larger force results in greater acceleration.

Newton's Third Law

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

Example of Newton's Third Law

The force exerted by a rocket engine pushes the rocket upward, while the exhaust gases are pushed downward.

Resultant Force

The single force that has the same effect as all the forces acting on an object combined.

Example of Resultant Force

Two people pushing a box in the same direction with forces of 10 N and 15 N have a resultant force of 25 N.

Equilibrium

When the resultant force on an object is zero, the object is in equilibrium.

Example of Equilibrium

A hanging picture frame remains stationary because the upward tension in the wire balances the downward gravitational force.

Moment of a Force

The turning effect of a force about a pivot.

Example of Moment of a Force

Using a longer spanner increases the moment, making it easier to turn a bolt.

Principle of Moments

For an object in equilibrium, the sum of the clockwise moments about a pivot equals the sum of the anticlockwise moments.

Example of Principle of Moments

A seesaw is balanced when the moments on either side of the pivot are equal.

Kinetic Energy

Energy of motion.

Example of Kinetic Energy

A moving car has kinetic energy.

Potential Energy

Stored energy due to position or state.

Gravitational Potential Energy

The energy an object possesses due to its position in the gravitational field.

Example of Gravitational Potential Energy

A book on a shelf has gravitational potential energy.

Elastic Potential Energy

Energy stored in stretched or compressed objects.