OAR Mechanical Comprehension exam 2024/2025 with 100% correct answers
1 view 0 purchase
Course
OAR Mechanical Comprehension
Institution
OAR Mechanical Comprehension
What is a lever? correct answersA simple machine that provides a mechanical advantage in carrying loads. Composed of a fulcrum (or pivot) and rigid rod (or beam).
What is the formula for calculating the load or the effort of a lever? correct answersW1 x L1 = W2 x L2 (Weight of the load x distanc...
What is a lever? correct answersA simple machine that provides a mechanical advantage in carrying
loads. Composed of a fulcrum (or pivot) and rigid rod (or beam).
What is the formula for calculating the load or the effort of a lever? correct answersW1 x L1 = W2 x L2
(Weight of the load x distance of the load from the fulcrum = weight of the effort x distance from the
fulcrum to the effort.)
What is a first class lever? correct answersA lever where the fulcrum is located between the force and
the load. ie. seesaw
What is a second class lever? correct answersA lever where the load (weight) is located between the
force (or effort) and fulcrum. ie. wheelbarrow, bottle opener, nutcracker. Best suited for carrying heavy
loads.
What is a third class lever? correct answersA lever where the force is located between the load and the
fulcrum. ie. chopsticks, tweezers. Used for accuracy rather than weight.
What is a gear? correct answersA wheel with equally sized and spaced teeth located on the
circumference.
What is the first rule of thumb in meshed gears? correct answersAdjacent gears rotate in opposite
directions.
If a gear system has an even number of cogwheels then...? correct answersThe last cogwheel will turn in
the direction opposite the first wheel.
If a gear system has an odd number of cogwheels then...? correct answersThe last cogwheel will turn in
the same direction as the first wheel.
, What is the second rule of thumb in meshed gears? correct answersThe velocity of the meshed
cogwheels is proportional to the number of teeth. ie. larger the wheel, the slower it turns.
What is the equation for calculating the velocity of meshed cogwheels? correct answersN1 x V1 = N2 x
V2 (Number of teeth in wheel one x velocity of wheel one = Number of teeth in wheel two x velocity of
wheel two)
Velocity of meshed gears can also be calculated using what? correct answersGear Ratio. Gear ration = n1
over/ n2 = v1 over/ v2
What are the three types of pulley systems? correct answersFixed, moveable, and combined.
What is the friction between components in a pulley system? correct answersZero.
What is the transfer of force in a pulley system? correct answersMaximum.
What is a fixed pulley? correct answersA pulley attached to a surface, like a crane or the ceiling.
What kind of advantage do fixed pulleys provide? correct answersThey provide directional advantage.
They do not provide an advantage in lifting loads. They do not change the direction of the force, so the
force must be used in an upward direction. The ceiling carries half the load in this instance because the
weight is divided equally between both parts of the rope.
What is a moveable pulley? correct answersA pulley attached directly to the load.
What is the ratio of the force required to lift a mass with the moveable pulley system? correct
answersThe force required to lift anything is inversely proportional to the distance the rope is pulled. So
if the rope is pulled four inches, the weight is lifted two inches.
What is the force required to lift a weight with a combined pulley system? correct answersThe force
required to lift a weight is divided by the number of load-supporting ropes used to lift the weight (don't
count the rope you're using to pull the weight.)
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller QUILLSKY. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $13.99. You're not tied to anything after your purchase.
