OAR OAR Mechanical Reasoning 5 — Questions and Answers
Question 1: A cam converts rotational motion into which type of motion?
- Rotational motion at a different speed
- Circular motion in the opposite direction
- Reciprocating (back-and-forth) linear motion (Correct answer)
- Oscillating pendulum motion
Correct answer: Reciprocating (back-and-forth) linear motion
A cam's irregular profile converts the rotational input into linear reciprocating motion in the follower.
Question 2: A 500 N load is lifted using a ramp that is 5 m long and 1 m high. Ignoring friction, what effort force is required to push the load up the ramp?
- 50 N
- 100 N (Correct answer)
- 250 N
- 500 N
Correct answer: 100 N
Mechanical advantage of inclined plane = length/height = 5; Force = 500/5 = 100 N.
Question 3: Which of the following is the BEST conductor of electricity?
- Carbon
- Silicon
- Copper (Correct answer)
- Iron
Correct answer: Copper
Copper has very low electrical resistivity and is the most common electrical conductor used in wiring.
Question 4: A pitch propeller creates thrust by pushing water backward. If a propeller's pitch is 12 inches, it theoretically advances how far per revolution?
- 1 inch
- 6 inches
- 12 inches (Correct answer)
- 24 inches
Correct answer: 12 inches
Propeller pitch is the theoretical distance it advances through the water in one full revolution.
Question 5: A sound wave travels from air into water. Its speed will:
- Decrease because water is denser
- Stay the same as in air
- Increase because water transmits sound better (Correct answer)
- Become zero since water absorbs sound
Correct answer: Increase because water transmits sound better
Sound travels approximately 4.3 times faster in water than in air due to water's greater bulk modulus.
Question 6: A wrench slips off a bolt head because the wrench opening is slightly too large. This is most likely to cause:
- The bolt to over-tighten
- The bolt head to round off (strip) (Correct answer)
- The wrench handle to bend
- No damage if turned slowly
Correct answer: The bolt head to round off (strip)
An oversized wrench rocks on the corners of the bolt head, shearing them off and rounding the head.
Question 7: A flywheel stores energy as rotational kinetic energy. Doubling its rotational speed will change its stored energy by a factor of:
- 2 (doubles)
- 4 (quadruples) (Correct answer)
- 8 (octuples)
- 0.5 (halves)
Correct answer: 4 (quadruples)
Rotational KE = ½Iω²; doubling ω (speed) squares the effect, quadrupling the stored energy.
OAR OAR Mechanical Reasoning 5
A cam converts rotational motion into which type of motion?