Chapter 3 Flashcards
Explain the difference between potential and kinetic energy
Kinetic is energy in motion
Potential is stored energy
What two units are used to describe mechanical force
Pounds
Or
Newtons
Two distinct qualities of mechanical force
Magnitude
Direction
Scaler vs vector value
Secular value has only magnitude
Vectors have magnitude AND direction
Formula for torque
Torque in lb-ft (N-m)
Equals
Force in pounds
X
Length of lever in ft (or meters)
How would you find torque in a rotating wheel?
A 6 in radius wheel pulled by a pull motor starter that is 6 inches long
The lever arm is the radius of the wheel and the force is applied at the edge of the wheel
Torque equals 15 lb-ft
Definition of mechanical work
- applied FORCE must act on an object
2. Object must MOVE while force is applied
Formula for mechanical work
Mechanical Work (in ft-lb) Equals
Force applied to an object
X
Distance moved in feet
One radian equals
57.296 degrees
Work done by torque formula
Work (done by torque in ft-lbs) Equals Force applied by torque in ft-lbs X angel of oration (in radians)
W=T x theta
What is formula for amount f work done by torque in horsepower
Torque Equals Rated horsepower x 5252 Dived by Rated speed in RPM
List the 6 simple machines
WIPSLW Wheel and Axle Incline Planes Pulley Screw Lever Wedge
1st class lever
Where is fulcrum,load and effort
EFFFORT FULCRUM LOAD
Pliers are a 1st class lever
1st grade Sea saw
2nd class lever
Where is load fulcrum and effort
FULCRUM LOAD EFFORT
like a wheel barrow where the fulcrum is the wheel
2nd grade Moving
3rd class lever
Where is fulcrum load and effort
LOAD EFFORT FULCRUM
Throwing a baseball
3rd grade-t ball!
What is sacrificed so that effort is minimized
Distance
Definition of mechanical advantage
The ratio of the input to the output force converted by a simple machine
Mechanical advantage of a wheel and axle
Is the ratio between the wheel RADIUS and the axle RADIUS
Lever on a wheel is
Always the radius
How to determine force required for lifting a load on a block and pulley
i.e. A 200lb load support by 5 ropes(not including final rope)
Divide the load force by the number of support ropes
(Does NOT include final rope)
Requires 40 pounds of downward force
MA of an incline plane
Is the vertical distance raised in ratio to the distance moved (the hypotenuse)
Work is
Equal to force
Times
Distance
A grooved pulley
Called a sheave
Why does a pulley provide MA
Because it allows the load to be supported by more than one rope
Equilibrium
A plane
All forces acting on an object cancel eachother
Something can be at equilibrium and still move though…
A plane canceling gravity wth the jets still glides
List the 6 types of energy
MECHLiNe mechanical Electrical Chemical Heat Light Nuclear
