OAR MECHANICAL
COMPREHENSION PRACTICE SET
2026 TESTED QUESTIONS AND
CORRECT SOLUTIONS
◉ When a bimetallic strip made of two different metals is heated, it
bends in a certain direction. What causes this bending? Answer: unequal
rate of thermal expansion of the two different metals
◉ What is the primary reason gears are used in mechanical systems?
Answer: Gears are primarily used to transfer power from one part of a
mechanical system to another. They can also change the speed and
direction of motion, but their main purpose is power transmission.
◉ In a pulley system, what is the mechanical advantage of using three
movable pulleys and one fixed pulley? Answer: The mechanical
advantage in a pulley system is determined by counting the number of
rope segments supporting the load. In this case, there are four segments
of rope supporting the load, providing a mechanical advantage of 4.
◉ What is the effect of a longer lever arm in a simple lever system?
Answer: A longer lever arm increases the mechanical advantage in a
lever system. It allows a larger load to be lifted with less effort.
◉ Which type of heat transfer occurs primarily in fluids (gases and
liquids)? Answer: Convection is the primary type of heat transfer in
, fluids. It involves the movement of warmer particles transferring heat to
cooler areas within the fluid.
◉ In a four-stroke internal combustion engine, what is the sequence of
the four strokes? Answer: The sequence in a four-stroke internal
combustion engine is: Intake (air-fuel mixture enters), Compression
(mixture is compressed), Power (spark ignites the mixture, causing an
explosion), Exhaust (expelled gases are removed).
◉ What is the primary purpose of a centrifugal clutch in a machine?
Answer: A centrifugal clutch engages automatically when the engine
reaches a certain speed, using centrifugal force to connect the drive shaft
without manual intervention.
◉ What principle explains the lifting force experienced by an airplane
wing? Answer: Bernoulli's Principle, which states that an increase in the
speed of a fluid occurs simultaneously with a decrease in pressure,
explains the lift force on an airplane wing. The wing's shape causes air
to move faster over the top surface, creating lower pressure compared to
the underside.
◉ In an electrical circuit, what is the function of a capacitor? Answer: A
capacitor stores electrical energy in an electric field. It is used in various
electrical circuits to store and release energy as needed.
◉ Why are ball bearings used in machinery? Answer: Ball bearings are
used to reduce friction between moving parts of machinery, thereby
increasing efficiency and reducing wear.
COMPREHENSION PRACTICE SET
2026 TESTED QUESTIONS AND
CORRECT SOLUTIONS
◉ When a bimetallic strip made of two different metals is heated, it
bends in a certain direction. What causes this bending? Answer: unequal
rate of thermal expansion of the two different metals
◉ What is the primary reason gears are used in mechanical systems?
Answer: Gears are primarily used to transfer power from one part of a
mechanical system to another. They can also change the speed and
direction of motion, but their main purpose is power transmission.
◉ In a pulley system, what is the mechanical advantage of using three
movable pulleys and one fixed pulley? Answer: The mechanical
advantage in a pulley system is determined by counting the number of
rope segments supporting the load. In this case, there are four segments
of rope supporting the load, providing a mechanical advantage of 4.
◉ What is the effect of a longer lever arm in a simple lever system?
Answer: A longer lever arm increases the mechanical advantage in a
lever system. It allows a larger load to be lifted with less effort.
◉ Which type of heat transfer occurs primarily in fluids (gases and
liquids)? Answer: Convection is the primary type of heat transfer in
, fluids. It involves the movement of warmer particles transferring heat to
cooler areas within the fluid.
◉ In a four-stroke internal combustion engine, what is the sequence of
the four strokes? Answer: The sequence in a four-stroke internal
combustion engine is: Intake (air-fuel mixture enters), Compression
(mixture is compressed), Power (spark ignites the mixture, causing an
explosion), Exhaust (expelled gases are removed).
◉ What is the primary purpose of a centrifugal clutch in a machine?
Answer: A centrifugal clutch engages automatically when the engine
reaches a certain speed, using centrifugal force to connect the drive shaft
without manual intervention.
◉ What principle explains the lifting force experienced by an airplane
wing? Answer: Bernoulli's Principle, which states that an increase in the
speed of a fluid occurs simultaneously with a decrease in pressure,
explains the lift force on an airplane wing. The wing's shape causes air
to move faster over the top surface, creating lower pressure compared to
the underside.
◉ In an electrical circuit, what is the function of a capacitor? Answer: A
capacitor stores electrical energy in an electric field. It is used in various
electrical circuits to store and release energy as needed.
◉ Why are ball bearings used in machinery? Answer: Ball bearings are
used to reduce friction between moving parts of machinery, thereby
increasing efficiency and reducing wear.
