CBST CBST Mechanical Reasoning 2 — Questions and Answers
Question 1: A ramp 10 feet long raises a load 2 feet high. What is the mechanical advantage of this inclined plane?
- 5 (Correct answer)
- 2
- 10
- 0.2
Correct answer: 5
The mechanical advantage of an inclined plane is the length divided by the height: 10 ÷ 2 = 5.
Question 2: An electric motor draws 10 amps at 120 volts. What is its power consumption?
- 1,200 watts (Correct answer)
- 12 watts
- 120 watts
- 10,000 watts
Correct answer: 1,200 watts
Power (watts) = Voltage × Current = 120 × 10 = 1,200 watts.
Question 3: If a spring is compressed to half its natural length, what happens to the elastic potential energy stored?
- It quadruples (Correct answer)
- It doubles
- It stays the same
- It halves
Correct answer: It quadruples
Elastic potential energy = ½kx², so doubling the compression (from half to full) quadruples the energy stored.
Question 4: A flat-head screwdriver is being used as a pry bar. What simple machine principle does this represent?
- A lever (Correct answer)
- A wedge
- An inclined plane
- A wheel and axle
Correct answer: A lever
When used as a pry bar, the screwdriver acts as a lever with the edge of the object serving as the fulcrum.
Question 5: Which of the following best explains why a thermostat uses a bimetallic strip?
- Different metals expand at different rates when heated (Correct answer)
- Metals conduct electricity differently
- One metal is magnetic and one is not
- The strip amplifies small temperature changes
Correct answer: Different metals expand at different rates when heated
A bimetallic strip bends when heated because the two bonded metals have different coefficients of thermal expansion.
Question 6: A car engine uses a flywheel. What is the primary function of a flywheel?
- To store rotational energy and smooth out power delivery (Correct answer)
- To increase engine speed
- To reduce fuel consumption
- To cool the engine
Correct answer: To store rotational energy and smooth out power delivery
A flywheel stores kinetic energy during power strokes and releases it between strokes, providing smooth, continuous rotation.
CBST CBST Mechanical Reasoning 2
A ramp 10 feet long raises a load 2 feet high.
What is the mechanical advantage of this inclined plane?