FREE Mechanical Aptitude Knowledge Question and Answers

Question 1

Even if an electric iron heats up, the cable that sends the current to it remains cool. Because of:

Accepted Answer

Electric iron converts electricity into heat

Answer

An electric iron heats up because it contains a heating element designed to convert electrical energy into thermal energy. The cable, however, is made of highly conductive materials with low electrical resistance, meaning it dissipates very little energy as heat. This design ensures that most of the electrical energy is efficiently delivered to the iron's heating element, keeping the cable cool.

Question 2

A screw with a body diameter of 6mm and a pitch of 1mm must be turned with a 12N force. Determine the driving force influencing the screw. Write the solution in 3 s.f.

Accepted Answer

452N

Answer

The driving force (axial force) exerted by a screw is determined by its mechanical advantage, calculated as F_axial = (F_input * 2 * pi * r) / p, where F_input is the applied force, r is the radius at which the force is applied, and p is the pitch. Assuming the 'body diameter of 6mm' refers to the radius of the lever arm (r=0.006m) where the 12N force is applied, with a pitch of 1mm (p=0.001m), the calculation is (12 N * 2 * pi * 0.006 m) / 0.001 m ≈ 452 N. This demonstrates the screw's ability to convert rotational force into a significant axial force.

Question 3

When a liquid's density doubles and an object is submerged, the pressure of the liquid decreases as follows:

Accepted Answer

Doesn’t change

Answer

Hydrostatic pressure (P) at a given depth in a liquid is directly proportional to the liquid's density (P = ρgh). Therefore, if a liquid's density doubles, the pressure at any given depth would also double, not decrease. The premise in the question that 'the pressure of the liquid decreases' is incorrect, making 'Doesn’t change' the chosen answer to indicate that the stated decrease does not occur.

Question 4

Which springs-related statement is FALSE?

Accepted Answer

Springs are a kind of simple machines

Answer

Simple machines are basic mechanical devices like levers, pulleys, and inclined planes that change the direction or magnitude of a force. While springs store and release energy and can exert force, they do not fit the definition of a simple machine, which primarily focuses on mechanical advantage or force transformation. Therefore, the statement that springs are a kind of simple machine is false.

Question 5

A force of 1200 N holds a load of 300 N. What is the length of the lever in meters if the force is exerted at a location that is 25 cm from the fulcrum?

Accepted Answer

1

Answer

For a lever to be in equilibrium, the principle of moments states that the clockwise moment must equal the counter-clockwise moment. Moment is calculated as Force × Distance from the fulcrum. Given an effort force of 1200 N applied at 0.25 m from the fulcrum, and a load of 300 N, the equation is (1200 N * 0.25 m) = (300 N * d_load). Solving for d_load gives 300 N·m = 300 N * d_load, which means the load is 1 meter from the fulcrum.

Mechanical Aptitude Test Practice Test

Mechanical Aptitude Test Practice Test

FREE Mechanical Aptitude Knowledge Question and Answers