OAR OAR Mechanical Reasoning 4

Question 1

A boat floats because the buoyant force equals its weight. If cargo is added until the boat sinks lower in the water, the buoyant force:

Accepted Answer

Increases as more water is displaced

Answer

Buoyant force equals the weight of displaced water, which increases as the boat sinks deeper.

Question 2

A screw with 20 threads per inch is turned 5 full rotations. How far does it advance into the material?

Accepted Answer

1/4 inch

Answer

Each rotation advances the screw 1/20 inch; 5 rotations × (1/20 in) = 1/4 inch.

Question 3

A refrigerator removes heat from inside by using a refrigerant. The compressor's role in this cycle is to:

Accepted Answer

Pressurize the refrigerant so it can release heat outside

Answer

The compressor raises refrigerant pressure, causing it to condense and release absorbed heat at the condenser coils outside.

Question 4

A 60 kg person stands on a scale in an elevator accelerating upward at 2 m/s². What does the scale read? (g = 10 m/s²)

Accepted Answer

720 N

Answer

Scale reads N = m(g + a) = 60 × (10 + 2) = 720 N.

Question 5

Three resistors of 6 Ω each are connected in parallel. What is the total resistance of the circuit?

Accepted Answer

2 Ω

Answer

For N equal resistors in parallel: R_total = R/N = 6/3 = 2 Ω.

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