Forces and Motion

Flashcards for Forces and Motion Study Guide

Force

A push or pull that causes a change in motion; a vector quantity with magnitude and direction, measured in Newtons (N).

Newton (N)

The unit of force in the metric system; defined by the equation F=m*a, where F is force, m is mass, and a is acceleration.

F=m*a

Equation defining force, where F is force (N), m is mass (kg), and a is acceleration (m/s²).

Gravitational Force

The force that pulls objects with mass towards each other.

Normal Force

Support force exerted by a surface on an object.

Friction

A force that opposes motion between two surfaces.

Tension

Force transmitted through a rope, string, or cable when it is pulled tight by forces acting from opposite ends.

Air Resistance

Friction experienced by an object moving through air.

Applied Force

A force that is directly applied to an object by a person or another object.

Newton's First Law (Inertia)

An object stays at rest or moves at constant velocity unless acted on by an unbalanced force.

Inertia

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

Newton's Second Law

Explains how force causes acceleration (F=m*a).

Newton's Third Law

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

Mass

The amount of matter in an object (kg); it is universal and doesn't change based on location.

Weight

The force of gravity acting on an object's mass (N); it changes based on location.

W=m*g

Equation for weight, where W is weight (N), m is mass (kg), and g is the acceleration due to gravity (approximately 9.8 m/s² on Earth).

Static Friction

Friction that keeps objects from starting to move.

Sliding Friction

Friction that slows down objects already in motion.

Rolling Friction

Friction that occurs when an object rolls over a surface; generally less than sliding friction.

Fluid Friction

Resistance experienced by an object moving through a fluid (air or water).

Speed

The rate at which an object covers distance (Speed = Distance/Time).

Velocity

Speed with direction.

Acceleration

The rate at which an object's velocity changes (a = (vf - vi)/t).

Work

Done when a force moves something.

Power

The rate at which work is done.

Kinetic Energy

Energy due to motion.

Gravitational Potential Energy

Energy stored in an object due to its height above a reference point.

Law of Conservation of Energy

Total energy is constant; it just transforms from one form to another.

Free Fall

Motion under the influence of gravity alone, without air resistance.

Terminal Velocity

The constant velocity of a falling object when the force of air resistance equals the force of gravity.

Machine

A device that changes the force or distance in a system to make work easier, but doesn't reduce the total work done.

Mechanical Advantage (MA)

The ratio of output force to input force (MA = Output Force / Input Force).

Ideal Mechanical Advantage (IMA)

The mechanical advantage of a machine assuming no energy loss due to friction (IMA = Input Distance / Output Distance).

Efficiency of a Machine

The ratio of output work to input work, expressed as a percentage (Efficiency = (Output Work / Input Work) * 100).

Simple Machines

Basic mechanical devices that multiply force or change direction: pulley, lever, wheel and axle, wedge, inclined plane, screw.

Inclined Plane

A flat surface set at an angle, used to reduce the force required to lift an object by spreading the force over a longer distance.

Pulley Systems

Arrangements of pulleys and ropes used to lift or move objects, providing mechanical advantage.

Single Fixed Pulley

A pulley that changes the direction of force (MA = 1).

Movable Pulley

A pulley that reduces the input force needed (MA > 1).

Block and Tackle

A combination of fixed and movable pulleys for greater mechanical advantage.

Force (Equation)

F=ma

Weight (Equation)

W=mg

Speed (Equation)

v=d/t

Acceleration (Equation)

a=(final velocity - start)/time

Momentum (Equation)

p=mv

Work (Equation)

W=Fd

Power (Equation)

P=W/t

Change in Velocity of Falling Object (Equation)

ΔV=gravity x time

Mechanical Advantage (Equation)

Fout/Fin

Efficiency (Equation)

(Wout/Win) x 100

Earth's Gravity

9.8 m/s²