ASVAB Mechanical

Pressure

Force (in pounds) / Area (in square inches)

Gravity

Physical property that draws objects toward the center of Earth. Generates a weight force when multiplied by an object’s mass.

Applied force

Force a person or another object applies to an object through contact

Tension

Transmitted through string, rope, etc when forces are acting on opposite ends

Friction

Resistance to the motion of two objects or surfaces that touch (opposite to object’s motion)

Recoil

Occurs when something regains its original form when an object exerting force on it is removed; it’s also referred to as a spring force

Law of universal gravitation

Every object in the universe attracts every other object in the universe

Centrifugal force

The apparent outward force on a mass when it is rotated (tangent to the circle)

Centripetal force

The force that keeps an object moving in a circular path (always points toward the center of the circle, perpendicular to the direction of motion of an object)

Which is less: rolling friction or sliding friction?

Rolling friction

Spring force (elastic recoil)

S_{f} = Spring Constant x Distance Displaced

Work

Work = Force x Distance

Power

P = W/t (measured in watts)

Mechanical Advantage

Mechanical Advantage = Resistance/Effort = Output Force / Input Force

Mechanical Advantage (Lever)

MA = (Effort Arm Length) / (Resistance Arm Length)

Mechanical Advantage (wheel and axle)

MA = (Wheel Radius) / (Axle Radius)

Mechanical Advantage (pulley)

MA = Number of rope segments supporting the load

Mechanical Advantage (plane)

MA = (Slope Length) / (Slope Height)

Mechanical Advantage (wedge)

MA = (Wedge Length) / (Wedge Thickness)

Mechanical Advantage (screw)

MA = (Circumference) / (Pitch of threads)

1st class lever

Fulcrum between effort and load (seesaw)

2nd class lever

Load between fulcrum and effort (wheelbarrow)

3rd class lever

Effort between fulcrum and load (shovel)

Load

Object or resistance you’re trying to move

Effort

Force you apply to move the load

Conservation of Work in Ideal Machines (gears, hydraulics, etc)

s_1t_1=s_2t_2

Which MA formula is used for simple machines like levers?

MA=LD/EF=LDd/EFd

What MA formula is for mechanical advantage of 2 gear system:

MA=Ta/Td

What MA formula is Mechanical Advantage of inclined plane:

MA= Length of Slope/Height of Slope

What formula is for Mechanical Advantage of Class 1 lever?

MA=Df-e/Df-l=Ld/Ef

What is the formula for MA Class 2 lever?

MA=De/Dl

What is the formula for MA Class 3 lever?

MA=LD/EF

What is the formula for Mechanical advantage of a screw?

MA=DE/DL=2(PI)L/DL

What is the Mechanical Advantage of a Wedge?

MA=Length of Slope/Width of Slope

What is a formula for pressure?

P=F/A=PGH

What is the formula for MA of Hydraulic Lift?

MA=D1/D2=A2/A1

Volume for Flow Rate?

Rf=v/t

The degree to which a force causes an object to rotate

Torque is

Velocity involves both speed and direction

Speed is different from velocity because

More

Compared to a similar mass, a larger mass requires _____________ Force to achieve the same acceleration rate.

Force is a scalar quality /quantity

Which of the following statements about force is NOT true?

A mechanism

Mechanics advantage is the advantage gained by the use of ________________ in transmitting Force.

Experiences kinetic friction

A hockey puck sliding on the ice

In a clockwise direction

If gear A turns in a counterclockwise direction, how does gear B turn?

Weight is totally dependent on mass

Which of the following statements about weight is NOT true?

The coefficient of static friction is dependent on the nature of the surface the box is resting on

While attempting to push a heavy box across the floor,

4:1

Which of the following represents the mechanical advantage of a wheel and axle system where the driven wheel has a radius of 10" and the drive wheel has a diameter of 5"?

60 pounds

If it takes a force of 20 pounds to stretch the spring one inch, how much force must be applied to stretch the spring three inches?

Use a longer wrench

In order to apply more torque to a bolt, mechanic could

The ent force acting on the vehicle is zero

A vehicle travels at a constant speed on the highway. It can be said that

Tower B will release more water than tower A

The two water towers below are of equal size and height above the ground. If both towers are completely full and their valves are opened, which of the following statements is true?

The cords holding sign B are under 1/3 the tension of the cord holding sign A

Two signs of equal weight are attached to a beam, using cords of equal length. Which of the following statements is true?

First- class lever

The illustration below is an example of which kind of lever?

10 m/s

If a vehicle accerates from a standstill at a rate of 1 m/s^2 , it's velocity after 10 seconds will be

A second-class lever

A wheelbarrow , as pictured below, is an example of

Gear Y moves moves counterclockwise

The gears in the illustration all have the same number of teeth. If gear X moves clockwise, which statement about gear Y is true?