Mechanical Aptitude Mechanical Aptitude Knowledge 4

Question 1

A 10 kg object sits on a frictionless inclined plane at 30°. What force parallel to the slope is needed to hold it stationary? (g = 10 m/s²)

Accepted Answer

50 N

Answer

Force along slope = mg × sin(30°) = 100 × 0.5 = 50 N.

Question 2

Which valve type is best for on/off control with minimal flow restriction when fully open?

Accepted Answer

Gate valve

Answer

Gate valves have a flat gate that lifts completely out of the flow path, offering very low resistance when fully open.

Question 3

The mechanical advantage of a wheel and axle is calculated as:

Accepted Answer

Wheel radius ÷ axle radius

Answer

MA = Wheel radius ÷ Axle radius; the larger the wheel compared to the axle, the greater the mechanical advantage.

Question 4

What happens to electrical resistance when the length of a wire is doubled?

Accepted Answer

Resistance doubles

Answer

Resistance is directly proportional to wire length: R = ρL/A, so doubling L doubles R.

Question 5

A centrifugal pump is running but not moving fluid. The most likely cause is:

Accepted Answer

Pump is cavitating due to air in the suction line

Answer

Air entrainment in the suction line prevents the pump from building pressure, causing it to lose prime and stop moving fluid.

Mechanical Aptitude Test Practice Test