Simple Machines

Question 1

Equation to find work

Answer 1

work= force x distance

- if the distance you move an object increases, the force required decreases

Question 2

Mass

Answer 2

• amount of matter an object contains
• mass of an object cannot change unless a part of the object is lost or another part is added
• measured in kg

Question 3

Effort

Answer 3

the force you put in to move or change the position of an object

Question 4

load

Answer 4

the weight of the object being lifted or carried

Question 5

Ist class lever

Answer 5

LiFE

• direction changer
• force multiplier

Question 6

2nd class lever

Answer 6

ELF

-Force multiplier

Question 7

3rd class lever

Answer 7

LEaF

-speed multiplier

Question 8

Force multipliers

Answer 8

• change small applied force into larger resultant force

Example: tweezer, crowbar

Question 9

Speed multiplier

Answer 9

Slow speed into faster resultant speed

Example: Car wheels, egg beaters

Question 10

Direction changers

Answer 10

-machines that change the direction in which a force acts

Example: blinds

Question 11

Can a machine be a speed+force multiplier?

Answer 11

No machine is both a speed and a force multiplier because then you’d get more work out than you put in

Question 12

Work

Answer 12

• energy required to move an object over a certain distance

- measured in joules (J)

Question 13

relationship equation of work input and work output

Answer 13

work input=work output (approximately)
(Fe x De)=(Fl x Dl)
Less useable energy comes out that what was put in because energy can be lost due to heat loss, friction, etc.

Question 14

Efficiency of a machine (as a %)

Answer 14

energy output/ energy input x 100

Question 15

MA (Levers)

Answer 15

dE/dL

fL/fE

Question 16

Speed multiplier or force multiplier?

Answer 16

Speed multiplier = mechanical advantage 1

Question 17

Gears

Answer 17

Wheels with teeth

When one gear turns, the one it interlocks with also turns but in the opposite direction

Question 18

Driver or driven?

Answer 18

Driver gear- gear turned first

Driven gear- turned by driver gear

Question 19

Gears- force multiplier or speed multiplier?

Answer 19

force- when effort is applied to smaller gear, the larger gear will turn more slowly but with greater force
speed- when effort is applied to larger gear, smaller gear will turn faster.

Question 20

idler gear

Answer 20

used in between driver and driven gear to make them turn in the same direction

Question 21

Bevel gear

Answer 21

positioned at right angles to one another to change the plane of rotation

Question 22

Rack and pinion

Answer 22

made up of a row of teeth -rack- and a gear wheel that rolls on top of this -pinion- which converts rotational movement into linear movement.

Question 23

MA of gears

Answer 23

no. teeth on driven/ no. teeth on driver

Question 24

gear ratios

Answer 24

no. teeth on driver/ no. teeth on driven

Question 25

Chain drives in a bicycle

Answer 25

- reduce slipping by having toothed gears - the gear used in a bicycle is called a rear sprocket wheel. - the pedal is attached to the chain drive which is then attached to the rear sprocket wheel

Question 26

High gear

Answer 26

- Faster speed - Flat roads - rear sprocket wheel is smaller, chain wheel is larger

Question 27

Low gear

Answer 27

-Slower speed -greater force -uphill rear sprocket is larger, chain wheel is smaller

Question 28

What is a pulley?

Answer 28

- A pulley is a wheel with a groove around it which can fit a rope. - Pulley is a form of lever, with its axle as the pivot/fulcrum

Question 29

Simple pulley system

Answer 29

- pulley system that lifts a weight up when another end of the rope is pulled down - direction changer

Question 30

Compound pulley system

Answer 30

- when there are two or more pulleys to lift the same load. - You have to pull the rope twice as far - force multiplier.

Question 31

Pulleys: the more times the rope supports the load...

Answer 31

the easier it is to lift (the more axles being used)

Question 32

MA of pulleys

Answer 32

-calculated by counting the number of ropes supporting the load (rope where effort is applied is not counted.

Question 33

Inclined plane

Answer 33

- flat surface that's higher on one end - they produce a ma by increasing the distance through which a force moves. - as the length of the slope increases and the height decreases, the effort required decreases.

Question 34

MA of inclined plane

Answer 34

length of slope/ height of inclined plane

Question 35

Screw

Answer 35

inclined plane wound around a central cylinder | Eg. drills+jar lids

Question 36

MA of screw

Answer 36

circumference/ pitch | pitch= 1/ no. of turns per inch

Question 37

Wedges

Answer 37

2 inclined planes joined back-to-back | used to split things

Question 38

MA of wedges

Answer 38

length of either slope/ thickness of big end

Question 39

MA of wheels+axles

Answer 39

radius of wheel/ radius of axle

Question 40

Speed multiplier- wheel and axle

Answer 40

When the input force is on wheel, output on axle

Question 41

Force multiplier- wheel and axle

Answer 41

input on axle, output on wheel