OAR MECHANICAL
COMPREHENSION REVIEW SHEET
2026 FULL QUESTIONS AND
ACCURATE ANSWERS
◉ If a driver completes a trip of 120 miles at a rate of 30mph, at what
rate would the driver have to travel on the return trip in order to average
40mph for the round trip? Answer: 30mph for 4 hours = 120 miles. So
round trip is 240 miles.
240 miles @ 40mph would take 6 hours.
She used up 4 hours on the way there, so she has to complete the last
120 miles in 2 hours.
D=R*T, R=60mph
◉ A bridge crosses a river that is 1520 feet wide. One bank of the river
holds 1/5 of the bridge and the other holds 1/6. How long is the bridge?
Answer: (1/6)*x + (1/5)*x + 1520 = x
Common denominator: 5x + 6x + 45600 = 30x
Solve for x = 2,400 feet long
◉ What is a fixed single pulley? Answer: 1 with 2 strings, i.e. a flag
pole
◉ What is a hydrometer? Answer: uses floats to measure specific
gravity. (weight of a liquid compared with weight of water. The liquid
,with the highest specific gravity will cause the float to rise higher in the
glass tube.
◉ What is a first class lever? Example? Answer: fulcrum is in the
middle i.e. scissors or pliers
◉ What is a second class lever? Example? Answer: fulcrum is at one
end and load is in between, i.e. nutcracker, wheelbarrow fulcrum is in
the wheel
◉ What is a third class lever? Example? Answer: fulcrum is at one end
and effort is between i.e. tongs, tweezers, fulcrum is in part of the tool
◉ in pulleys, which pulley will turn faster? Answer: the small puller will
turn faster than those larger than it
◉ What kind of plane is an axe? Answer: a wedge which is an inclined
plane
◉ Can electricity flow through a circuit with a burned out bulb?
Answer: no but a voltmeter can bypass it if connected on both sides
since it measures total voltage in a circut
◉ in a 2 pulley system, how much will the movable pulley move up?
Answer: only half the distance and spin half as much as the fixed pulley,
even if they are the same diameter
, ◉ Calculate the RPM if a wheel is spinning twice per second Answer:
take number of rods on the wheel, divide that from the needed contacts
per minute.
(ex. twice per second = 120 contacts per minute. 10 projection rods on
wheel. 120/10=12. must rotate at 12 rpm.
◉ When driver wheel is present how will the adjacent wheels rotate
Answer: closest to the center
◉ How do you increase the effort of the lever arm? Answer: Increase the
length and enable a valve to blow off at a higher pressure.
Moving the weight further away will do this
◉ How to read a micrometer Answer: Sleeve section: horizontal
cylindric shape; read as dollars and quarters
Thimble section: vertical cylindric shape; read as cents added to the
initial money^
the first part is contributed by the main scale on the sleeve
the second part is contributed by the rotating vernier scale on the thimble
(5+.5+.28=5.78mm)
COMPREHENSION REVIEW SHEET
2026 FULL QUESTIONS AND
ACCURATE ANSWERS
◉ If a driver completes a trip of 120 miles at a rate of 30mph, at what
rate would the driver have to travel on the return trip in order to average
40mph for the round trip? Answer: 30mph for 4 hours = 120 miles. So
round trip is 240 miles.
240 miles @ 40mph would take 6 hours.
She used up 4 hours on the way there, so she has to complete the last
120 miles in 2 hours.
D=R*T, R=60mph
◉ A bridge crosses a river that is 1520 feet wide. One bank of the river
holds 1/5 of the bridge and the other holds 1/6. How long is the bridge?
Answer: (1/6)*x + (1/5)*x + 1520 = x
Common denominator: 5x + 6x + 45600 = 30x
Solve for x = 2,400 feet long
◉ What is a fixed single pulley? Answer: 1 with 2 strings, i.e. a flag
pole
◉ What is a hydrometer? Answer: uses floats to measure specific
gravity. (weight of a liquid compared with weight of water. The liquid
,with the highest specific gravity will cause the float to rise higher in the
glass tube.
◉ What is a first class lever? Example? Answer: fulcrum is in the
middle i.e. scissors or pliers
◉ What is a second class lever? Example? Answer: fulcrum is at one
end and load is in between, i.e. nutcracker, wheelbarrow fulcrum is in
the wheel
◉ What is a third class lever? Example? Answer: fulcrum is at one end
and effort is between i.e. tongs, tweezers, fulcrum is in part of the tool
◉ in pulleys, which pulley will turn faster? Answer: the small puller will
turn faster than those larger than it
◉ What kind of plane is an axe? Answer: a wedge which is an inclined
plane
◉ Can electricity flow through a circuit with a burned out bulb?
Answer: no but a voltmeter can bypass it if connected on both sides
since it measures total voltage in a circut
◉ in a 2 pulley system, how much will the movable pulley move up?
Answer: only half the distance and spin half as much as the fixed pulley,
even if they are the same diameter
, ◉ Calculate the RPM if a wheel is spinning twice per second Answer:
take number of rods on the wheel, divide that from the needed contacts
per minute.
(ex. twice per second = 120 contacts per minute. 10 projection rods on
wheel. 120/10=12. must rotate at 12 rpm.
◉ When driver wheel is present how will the adjacent wheels rotate
Answer: closest to the center
◉ How do you increase the effort of the lever arm? Answer: Increase the
length and enable a valve to blow off at a higher pressure.
Moving the weight further away will do this
◉ How to read a micrometer Answer: Sleeve section: horizontal
cylindric shape; read as dollars and quarters
Thimble section: vertical cylindric shape; read as cents added to the
initial money^
the first part is contributed by the main scale on the sleeve
the second part is contributed by the rotating vernier scale on the thimble
(5+.5+.28=5.78mm)
