WORK, POWER, AND SIMPLE MACHINES

SCIENCE 8TH GRADE

work

work occurs when a force is used to move an object a distnace in the direction of the force

force x distance distance

Work

Work is measured in

Joules

work is equal to

Joules (J)

Force is equal to

Newtons (N)

distance is equal to

Meters (m)

in order to accomplish work on and object, there must be a ? to exerted on the object, and the object must move in the ? of the force

Force Direction

Force with no motion

when a force is exerted on an object which does not move, no work is done on the object

Force perpendicular to motion

When an object is arried at constant velocity by a force which act at right angies to the motion, no work is done

What is power?

the rate at which energy is transferred

Mechanical Advantage (MA) and efficiencey

Mechanical anvandtage (MA) tells you how much a machine multiplies your input (applied) force

the formula for MA is given by

MA= Output force

Input force

output force

is what the machine produce

input force

The force applied to a machine

The greater the MA indicates the ___________ force you need to apply. Therefore, to make your work easier, you should use a machine with a ___________ MA

Less high

relationship between between MA and input force in inversely proportional : ____________________, the required ________________

MA increases input force decreases

Calculating Mechanical Advantage

output force divided by input force

Friction Decreases Efficiency

Efficiency measures how effectively a machine converts input work into output work, expressed as a percentage

Simple Machines

Simple machines are used to make work easier.

Machines DO NOT change the amount of work done, instead, they allow for a trade off between force and distance.

simple machines

example, using a longer inclined plane requires less force but more distance to move an object

6 types of simple machines are

*Lever

**Wedge

***Screw

****Wheel & Axle

*Pulley

Inclined plane

Each has unique characteristics and applications

Types of simple Machines

lever, inclined plane, pulley, wheel & axel, wedge, screw

Lever

a simple machine that consists of a bar that pivots at a fixed point called a fulcrum

inclined plane

a slanted surface along which a force moves an object to a different elevation

Pulley

A simple machine consists of a grooved wheel wrapped around a rope or cable.

screw

is a common fastener with a threaded shaft and a head, designed to be driven into a material to secure objects together, often with a screwdriver or similar tool

Wedge

A device that is thick at one end and tapers to a thin edge at the other end.

wheel and axle

Two differently sized circular objects are attached and turn into one.