Machines

Question 1

Claw of archimedes

Answer 1

Was invented by archimedes as a sea defence
It uses pulleys to increase lifting capabilities by multiplying the force

Question 2

Trebuchet, catapult and ballista

Answer 2

Created by the Chinese as early as 4 century BC
Used to project missiles as they multiplied distance

Question 3

Quern stone

Answer 3

Had a handle to allow a heavy wheel to be turned within a channel
Used to grind meal/farm and multiplied force

Question 4

Archimedes screw

Answer 4

Invented by archimedes to help farmers along the Nile
Used as a water pump and multiplied force

Question 5

Pivot

Answer 5

Point that doesn’t move (fulcrum)

Question 6

Effort

Answer 6

Force put into the lever

Question 7

Load

Answer 7

Weight acting down

Question 8

What is easier the load close or far away from the pivot

Answer 8

The closer the load is to the pivot and further away from the effort the greater the mechanical advantage and therefore the easier to move

Question 9

What is a moment

Answer 9

A turning effect about a fixed point

Question 10

What are the calculations for a moment

Answer 10

Moment=force x perpendicular distance from 5he effort to the pivot
Force =moment ➗ distance
Distance=moment ➗ force

Question 11

How do moments usually exist

Answer 11

Moment usually exist together. One will act a clockwise direct the other an anti clockwise dircetion.
This means fd AWC= fd CW

Question 12

When a system is balanced……

Answer 12

Mathematically, the AWC moment is equal to the CW moment

Question 13

Another word for balanced

Answer 13

Equilibrium

Question 14

What are gears used for

Answer 14

They are used to transfer forces and motion from one object to another

Question 15

What can gears change

Answer 15

Speed
Direction
Torque

Question 16

What do gears have that allow them to interlock

Answer 16

Teeth that interlock into other teeth from an another gear. This is called meshing

Question 17

Gear train

Answer 17

When three or more gears mesh

Question 18

Describe a diagram of a gear

Answer 18

Overall thing is a gear
Part between the two gear is the meshing area
Around the edges are the teeth
In the centre is the axle that the gear turns on

Question 19

How are gears and wheels similar but different

Answer 19

They both have an axle and are round but only gears have teeth

Question 20

Name some types of gears

Answer 20

Helical gear(one thick Twisty gear)
Spur gear(one small gear and one bigger gear)
Rack and pinion gear(long thin rack with gear on it)
Worm gear(worm comes out of bottom gear and worm on top)
Bevel gear(turns on a 90 degree angle)
Sprocket gear(rocket shape teeth)

Question 21

If one gear rotates one direction (clockwise) the next one in the train will rotate….

Answer 21

The opposite direction(anti-clockwise )

Question 22

Driver gear

Answer 22

initiates the movement of the entire gear train

Question 23

If the driver gear is bigger than the driven

Answer 23

Is multiplies speed

Question 24

If the driver gear is smaller then the driven gear

Answer 24

It multiplies force

Question 25

How do you calculate how many times a driver gear will turn the driven

Answer 25

Count the teeth on both Look at how many times the driven gear needs to rotate to equal the number of teeth of the driver

Question 26

What is the formula for the ratio for rotations of the gear

Answer 26

Ration=driven teeth ➗ driver teeth

Question 27

The more ropes holding a load

Answer 27

The less effort required

Question 28

What is the triangle for pulleys

Answer 28

Effort=Load ➗ No. ropes Load= Effort x No. ropes No.ropes= Load ➗ Effort

Question 29

Although the more ropes supporting a load the less efffort required what does become greater

Answer 29

The length of the rope fed through (more will be needed)

Question 30

Why aren’t pulleys 100% efficient

Answer 30

Energy is lost to friction

Question 31

Energy transferred=

Answer 31

I.e the work done = Force x Distance

Question 32

What is a compound Gera

Answer 32

Two gears inside each other

Question 33

Fixed pulley

Answer 33

The wheel is fixed in a place and only changes direction not the force

Question 34

Moveable pulley

Answer 34

When the wheel moves with the load and effort and load move in the same direction

Question 35

Mechanical advantage

Answer 35

The amplification of a force

Question 36

Mechanical advantage formula =

Answer 36

Force out ➗ force in

Question 37

Energy used to lift a mass=

Answer 37

Force(magnitude) x distance over which the force acts

Question 38

What do all devices that generate mechanical advantage do

Answer 38

Covert a small force applied over a long distance into a large force applied over a short distance

Question 39

Torque for gears=

Answer 39

Force x distance to axis of rotation (radius of wheel) 🛞

Question 40

Gears mechanical advantage=

Answer 40

No. Follower teeth ➗ no. Driver teeth