forces - physics chapter 5

Scalar Quantity

A quantity that has only magnitude (size) and no direction. Examples: distance, time, speed, mass.

Vector Quantity

A quantity that has both magnitude and direction. Examples: velocity, displacement, momentum, acceleration.

Resultant Force

The overall force acting on an object, which can be calculated by adding or subtracting individual forces.

Force

A push or pull on an object due to the interaction with another object, measured in newtons (N).

Contact Forces

Forces that occur when two objects are physically touching, such as friction, tension, and normal contact force.

Non-Contact Forces

Forces that do not require objects to be in contact, like magnetic, gravitational, and electrostatic forces.

Mass

The amount of matter in an object, measured in kilograms (kg). It does not change regardless of gravity.

Weight

The amount of force acting on an object due to gravity, measured in newtons (N). Weight can be calculated as mass times gravitational field strength.

Gravitational Field Strength

A measure of the force of gravity at a specific location, measured in newtons per kilogram (N/kg).

Work Done

The energy transferred when a force moves an object over a distance, measured in joules (J) or newton meters (Nm).

Elastic Potential Energy

The energy stored in elastic materials as the result of their stretching or compressing.

Hooke’s Law

States that the extension of a spring is directly proportional to the force applied, until the limit of proportionality is reached.

Terminal Velocity

The maximum velocity attained by an object as it falls through a fluid, where the force of gravity equals the drag force.

Newton's First Law

An object at rest will stay at rest, and an object in motion will continue in motion at constant velocity unless acted upon by a resultant force.

Newton's Second Law

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

Newton's Third Law

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

Inertia

The tendency of an object to resist any change in its state of motion.

Momentum

The quantity of motion of a moving body, measured as a product of its mass and velocity.

Conservation of Momentum

In a closed system, the total momentum before an event is equal to the total momentum after the event.

Thinking Distance

The distance traveled by a vehicle during the time it takes for the driver to react to a hazard and apply the brakes.

Braking Distance

The distance it takes for a vehicle to stop under the force of the brakes after the brakes have been applied.

Stopping Distance

The total distance a vehicle travels while stopping, which is the sum of thinking distance and braking distance.

Friction

The resistive force that occurs when two surfaces contact each other, acting in the opposite direction to movement.

Kinetic Energy

The energy that an object possesses due to its motion, calculated as 0.5 x mass x velocity squared.

Extension

The increase in length of an elastic material when a force is applied.

Spring Constant (k)

A measure of the stiffness of a spring; it tells how much force is needed to compress or extend the spring by one meter.

Center of Mass

The point at which the weight of an object is considered to act, often used in calculating weight and balance.

Air Resistance

A type of frictional force experienced by objects moving through air, also known as drag.

Resistance

The opposition to the flow of electric current in a circuit, often caused by materials that do not conduct electricity well.

Vector Diagram

A visual representation of forces that shows their magnitude and direction, usually represented by arrows.

Free Body Diagram

A simplified representation of an object along with all the forces acting on it, shown as arrows pointing in the direction of the forces.

Energy Transfer

The process of energy moving from one place to another or changing from one form to another.

Acceleration

The rate at which an object changes its velocity, measured in meters per second squared (m/s²).

Speed

The distance traveled per unit of time, a scalar quantity measured in meters per second (m/s).

Velocity

The speed of an object in a specific direction, a vector quantity measured in meters per second (m/s).

Displacement

The distance moved in a specific direction from the starting point, a vector quantity.

Distance

The total path length traveled by an object, a scalar quantity.

Average Reaction Time

The typical time it takes for a person to respond to a stimulus, usually between 0.2 and 0.9 seconds.

Hydraulic System

A system that uses liquid under pressure to transmit force, commonly used in machinery and vehicles.

Work-Energy Principle

The principle stating that the work done on an object is equal to the energy transferred to it.

Fluid Dynamics

The study of the movement of liquids and gases, including the forces they exert.

Streamlined Design

A design that reduces drag by allowing fluids to flow over it more smoothly.

Drag Force

The resistance force experienced by an object moving through a fluid, such as air or water.

Thermal Energy

The energy that comes from the temperature of matter; it is the total energy of all the particles in an object.