Ch 11 Lesson 4--Simple Machines

simple machine

A tool that changes force, distance, or direction. Example: A ramp is a __ for moving boxes.

effort

The force you apply to a machine. Example: My __ on the rope lifted the bucket.

output

The force a machine supplies. Example: The __ from the lever raised the rock.

load

The object moved by the output. Example: The __ on the ramp was the heavy crate.

effort arm

The part of a machine that receives the effort. Example: I pushed on the __ to lift the load.

resistance arm

The part that delivers the output force. Example: The __ pushed up on the stone.

mechanical advantage

How much a machine multiplies effort. Example: A greater __ made lifting feel easier.

lever

A bar that rotates around a pivot point. Example: A __ helped me pry the lid open.

fulcrum

The pivot point of a lever. Example: The board balanced on the __ like a seesaw.

first-class lever

A lever with the fulcrum between effort and load. Example: A seesaw is a __ at the park.

second-class lever

A lever with the load between fulcrum and effort. Example: A wheelbarrow is a __ for dirt.

third-class lever

A lever with effort between fulcrum and load. Example: Tweezers act like a __ for tiny items.

wheel and axle

A wheel attached to a rod that turns. Example: The doorknob used a __ to open the door.

gears

Toothed wheels that turn together. Example: The bike used __ to help me pedal faster.

pulley

A grooved wheel with a rope. Example: The flag rose when I pulled the __ rope.

inclined plane

A ramp used to raise objects. Example: The mover used an __ to roll the box up.

wedge

An inclined plane used to separate objects. Example: A knife is a __ that cuts food.

screw

An inclined plane wrapped around a cylinder. Example: I turned the __ to hold the shelf tight.

compound machine

Two or more simple machines combined. Example: A bicycle is a __ with several parts.

efficiency

How much input energy becomes useful output. Example: Less friction increased the machine’s __.