OAR Mechanical Review
Work - answer Force x Distance or W = F x D
The application of force over a distance
Newtons - answerA unit of force
4.45 N = 1lb
Power (definition) - answerThe rate at which weight is moved
1 Horsepower equals? - answer33,000 pounds lifted 1 foot per minute
Electrical Power of 1 HP equals? - answer746 Watts (precisely 745.7)
Joule's Law (Power) - answerP = E x I
P = Power
E = Voltage
I = Current
Efficiency - answerWork-out/Work-in
Fraction is never greater than 1
Pressure - answerPressure = Force/Area
First Class Lever - answerFulcrum is in the middle (Ex. Scissors, Pliers)
Scissors are? - answera First Class Lever
Pliers are? - answera First Class Lever
Second Class Lever - answerFulcrum is at one end, load is in between (Ex. Nutcracker,
Wheelbarrow)
Nutcrackers are? - answerSecond Class Levers
Wheelbarrows are? - answerSecond Class Levers
Third Class Lever - answerFulcrum is at one end, effort is in between (Ex. Tongs,
tweezers)
, In Third Class levers, the load arm is longer than the effort arm, so the MA is less than
1.
Tongs are? - answerThird Class Levers
Tweezers are? - answerThird Class Levers
Mechanical Advantage (definition) - answerThe ratio of Load to Effort
MA = FL/FE
Lever systems rotate in equilibrium, meaning? - answerThe magnitudes of the opposing
torques (effort vs. resistance/load) are equal
(Force of Effort) times (Length/Distance of Effort Arm) = (Force of Resistance/Load)
times (Length/Distance of Resisting/Load Arm)
Mechanical Advantage of Levers - answerMA = Effort Arm/Resisting Arm
Wheel and Axle - answerSimilar to a lever: A force applied to the wheel causes the axle
to rotate, which can be used to magnify the output force.
Wheel and Axle Questions - answer- Mechanical Advantage = Radius of Axle to
handle/radius of drum
- Make sure you're using the RADIUS, not the diameter
Mechanical Advantage Inclined Plane - answerMA = Opposite Leg (or height) divided by
the Hypotenuse of a right triangle (Sin)
MA = Length of Effort (hypotenuse) divided by the Height
Wedge - answeris a double inclined plane
Examples of Wedges - answerAxes, knives, and chisels
Screws - answerIs an inclined plane wrapped around a cylinder.
Rotating the screw (applying torque), the force is applied perpendicular to the grove.
Mechanical Advantage of Pulleys - answerNumber of Ropes = Mechanical Advantage
Mechanical Advantage of Hydraulics/Pistons - answerMA = a2*d2=a1*d1
Terms: a = Area, d = Displacement
smaller D/bigger D = mechanical advantage
Work - answer Force x Distance or W = F x D
The application of force over a distance
Newtons - answerA unit of force
4.45 N = 1lb
Power (definition) - answerThe rate at which weight is moved
1 Horsepower equals? - answer33,000 pounds lifted 1 foot per minute
Electrical Power of 1 HP equals? - answer746 Watts (precisely 745.7)
Joule's Law (Power) - answerP = E x I
P = Power
E = Voltage
I = Current
Efficiency - answerWork-out/Work-in
Fraction is never greater than 1
Pressure - answerPressure = Force/Area
First Class Lever - answerFulcrum is in the middle (Ex. Scissors, Pliers)
Scissors are? - answera First Class Lever
Pliers are? - answera First Class Lever
Second Class Lever - answerFulcrum is at one end, load is in between (Ex. Nutcracker,
Wheelbarrow)
Nutcrackers are? - answerSecond Class Levers
Wheelbarrows are? - answerSecond Class Levers
Third Class Lever - answerFulcrum is at one end, effort is in between (Ex. Tongs,
tweezers)
, In Third Class levers, the load arm is longer than the effort arm, so the MA is less than
1.
Tongs are? - answerThird Class Levers
Tweezers are? - answerThird Class Levers
Mechanical Advantage (definition) - answerThe ratio of Load to Effort
MA = FL/FE
Lever systems rotate in equilibrium, meaning? - answerThe magnitudes of the opposing
torques (effort vs. resistance/load) are equal
(Force of Effort) times (Length/Distance of Effort Arm) = (Force of Resistance/Load)
times (Length/Distance of Resisting/Load Arm)
Mechanical Advantage of Levers - answerMA = Effort Arm/Resisting Arm
Wheel and Axle - answerSimilar to a lever: A force applied to the wheel causes the axle
to rotate, which can be used to magnify the output force.
Wheel and Axle Questions - answer- Mechanical Advantage = Radius of Axle to
handle/radius of drum
- Make sure you're using the RADIUS, not the diameter
Mechanical Advantage Inclined Plane - answerMA = Opposite Leg (or height) divided by
the Hypotenuse of a right triangle (Sin)
MA = Length of Effort (hypotenuse) divided by the Height
Wedge - answeris a double inclined plane
Examples of Wedges - answerAxes, knives, and chisels
Screws - answerIs an inclined plane wrapped around a cylinder.
Rotating the screw (applying torque), the force is applied perpendicular to the grove.
Mechanical Advantage of Pulleys - answerNumber of Ropes = Mechanical Advantage
Mechanical Advantage of Hydraulics/Pistons - answerMA = a2*d2=a1*d1
Terms: a = Area, d = Displacement
smaller D/bigger D = mechanical advantage
