ASTB Prep
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Mechanical Advantage of an Inclined Plane
Length of slope / Height of plane

Mechanical Advantage of Pulley
 Resistance Force (weight) / Effort Force
 OR
 # of ropes that support the pulley





Total # of degrees of a shape
(# of sides  2) * 180

Supplementary Angles
Addup to 180

Complementary Angles
Add up to 90

2 times r exceeds one half of t by 5
2r  .5 = 5

Questions regarding how fast people can do a job together
Time actually needed / Time can do the job alone = 1

Product has been discounted to a new price, what is the percent reduction?
 Old price  new price
 Difference / old price
 multiply numerator by 100, divide

You know details of one gear
How many revolutions of other gear?
 r = (D*R)/d
 #of teeth gear A * # revolutions of gear A / # teeth gear B

Specific Gravity
Weight of a liquid vs Weight of water

1st Class lever
 Fulcrum in the middle
 Scissors, Pliers

2nd class lever
 Fulcrum at one end, load in between
 Nutrcracker, Wheelbarrow

3rd class lever
 Fulcrum at one end, effort in between
 Tongs, Tweezers

Smaller pulley turns ____ than larger pulley
faster

Pioneer 10
First US craft to explore outer solar system

Characteristics of warm front
 Steady, long periods of rain
 Fog

Atmospheres: Lowest to highest
 Troposphere
 Stratosphere
 Mesosphere
 Thermosphere/Ionosphere/Aurora

Troposphere
 20k feet at poles
 60 k feet at equator

Stratoshere
120k ft (20 miles)

Mesosphere
300k ft (50 miles)

Boundary between Tropo and Stratosphere
Tropopause

Ozone layer
Located at higher end of stratosphere

You generally need oxygen if flying above
10k ft

Air composition
 78% Nitrogen
 21% Oxygen
 1% Argon
 Rest is CO2 and other rare gasses

An axe is classified as a
Wedge (Inclined Plane)

The farther away the fulcrum is from the resistance arm
 more force is required to lift the load
 higher resistance arm will travel

Current is _____ in a series

Voltage is _____ in parallel circuits


2 pulley system: movable and fixed pulley
 Movable pulley will only move half the distance
 Movable pulley will only spin half as much as fixed pulley

Finding RPM
Needed contacts per minute / # of rods on wheel

Pendulums
 Swing weight makes no difference
 Speed is dependent upon length of string

If you place an object evenly on 2 scales, each scale will
read half of the total weight.
True

4stroke engine
 Intake
 Compression
 Combustion
 Exhaust

Pressure formula
Force / Area

Momentum Equation
Force * Distance


Multimeter
Measures current, volt

Vise M.A.
(2*pi*length of handle) / pitch of thread


A naval detachment has enough rations to feed 16 people
for 10 days. If 4 more people join the detachment, for how many
fewer days will the rations last?
 1. Get the number of total rations available: 16 x 10 = 160 rations
 2. 4 people + 16 people: 20 people
 3. 160 rations divided amongst 20 people: 8 days
 4. 8 days is 2 less than 10 days

A field can be plowed by 9 machines in 5 hours. If 3
machines are broken and cannot be used, how many hours will it take
to plow the field?
 1. 9 machines in 5 hours: 45 machine hours
 2. 3 machines broken: 6 working
 3. 45/6: 7.5 hours

Lever Rules
 I. : MA (leverage) increases with length of lever arm, or placement of fulcrum
 II. Closer fulctrum to load: higher MA
 III. A lever arm in balance: forcexlength = forcexlength on both sides

Boyle's Law
 High volume: Low Pressure
 High Pressure: Low Volume

Charles' Law
 If gas is at constant pressure,
 High volume: high temperature
 Example: Heating gas doubles its temperature and volume

Bernoulli's Principle
As velocity of a fluid increases, pressure decreases