Basic Machines & Mechanical Advantage

Question 1

Lever

Answer 1

a bar that is free to move about a fixed point when an effort force is applied

Parts of a lever:
lever/bar
effort arm
load arm
fulcrum

levers are used to move a large resistance or load with a small effort

Question 2

Fulcrum

Answer 2

pivot point of a lever

Question 3

Lever equation

Answer 3

effort x effort arm = load x load arm

Question 4

mechanical advantage

Answer 4

moving a large resistance or load with a small amount of effort

actual mechanical advantage = force output / force input

work input is always equal to work out

Question 5

power

Answer 5

the rate at which work is done

Question 6

Class 1 levers

Answer 6

a lever with the fulcrum between the effort and the load

a see saw

Question 7

Class 2 levers

Answer 7

a lever with the fulcrum at the end of the bar

a wheelbarrow

the load is between the fulcrum and the person lifting the material (aka the effort)

Question 8

Class 3 levers

Answer 8

only lever with a mechanical disadvantage

a lever where the effort is applied between the fulcrum and the load

used to increase speed or distance the load moves compared to the distance the effort moves

snow plows; catapults

Question 9

inclined planes

Answer 9

a slanted surface used to raise an object

Total mechanical advantage = length of plane / height of plane

Question 10

Wedge

Answer 10

a double inclined plane

used for holding power

door stopper

Question 11

screw thread

Answer 11

uniform ridge formed into the surface of the cylinder

the diameter of the cylinder, the shape of the thread, and the number of threads per inch make of the specifications

a screw with 10 threads per inch is said to have a pitch of 0.1

pitch = 1 / numbers of threads per inch

the pitch determines MA

increasing the threads per inch decreases the pitch and increases the theoretical MA

TMA = distance effort moves / distance load moves or
2(3.14)r / pitch

Question 12

pulley

Answer 12

a simple machine that can be described as a wheel with a groove in the middle for a rope or cable

Question 13

single fixed pulley

Answer 13

changes the direction of the applied effort

Question 14

moveable pulleys

Answer 14

allow more ropes or cables to be attached

one type has a MA of 2:1
-you pull the lifting rope with half the effort, but twice as far as you want the load to move

Question 15

block and tackle

Answer 15

two or more pulleys on one axle that form a block

pulleys can be added to any lifting system and the MA changes with each added pulley