Free IST Mechanical Aptitude Questions and Answers — Questions and Answers
Question 1: Which type of simple machine is a seesaw?
- Lever (Correct answer)
- Pulley
- Inclined Plane
- Screw
Correct answer: Lever
A seesaw is a classic example of a lever, specifically a Class 1 lever. It consists of a rigid bar (the board) that pivots around a fixed point called a fulcrum (the central support). The effort force is applied on one side, and the load (the person) is on the other, demonstrating how levers can multiply force or change the direction of motion.
Question 2: If Gear A has 20 teeth and Gear B has 40 teeth, how many rotations will Gear A make when Gear B makes one rotation?
- 0.5 rotations
- 1 rotation
- 2 rotations (Correct answer)
- 4 rotations
Correct answer: 2 rotations
The relationship between the rotations of two meshed gears is inversely proportional to their number of teeth. Since Gear B has twice as many teeth as Gear A (40 teeth vs. 20 teeth), Gear A must rotate twice for every single rotation of Gear B to maintain the same linear speed at the point of contact. Therefore, Gear A will make 2 rotations.
Question 3: Which of the following describes the mechanical advantage of an inclined plane?
- The length of the plane divided by the height of the plane (Correct answer)
- The height of the plane divided by the length of the plane
- The weight of the load divided by the length of the plane
- The weight of the load divided by the height of the plane
Correct answer: The length of the plane divided by the height of the plane
The mechanical advantage (MA) of an inclined plane is calculated by dividing the length of the inclined surface by its vertical height. This ratio indicates how much the input force is multiplied, making it easier to move an object vertically by pushing it along a longer, gentler slope. A higher MA means less effort is required.
Question 4: Which principle explains why a hydraulic press can lift a heavy object with a small force?
- Archimedes' Principle
- Bernoulli's Principle
- Newton's Third Law
- Pascal's Principle (Correct answer)
Correct answer: Pascal's Principle
Pascal's Principle states that a pressure change at any point in a confined incompressible fluid is transmitted throughout the fluid such that the same change occurs everywhere. In a hydraulic press, a small force applied to a small piston creates pressure that is transmitted to a larger piston, resulting in a much larger force capable of lifting heavy objects.
Question 5: What happens to the effort force required to lift a load if the length of the lever arm is increased?
- It increases
- It decreases (Correct answer)
- It remains the same
- It fluctuates
Correct answer: It decreases
For a lever, the principle of moments (or torque) states that the effort force multiplied by the length of the effort arm equals the load force multiplied by the length of the load arm. If the length of the effort arm is increased while the load and load arm remain constant, the effort force required to balance or lift the load must decrease. This is why longer wrenches make it easier to turn bolts.
Question 6: In a wheel and axle system, what happens to the force applied if the radius of the wheel is larger than the radius of the axle?
- The force is multiplied (Correct answer)
- The force is reduced
- The force is equal
- The force is negated
Correct answer: The force is multiplied
A wheel and axle system functions as a type of lever, where the wheel acts as the effort arm and the axle as the load arm. When the force is applied to the larger radius wheel, it creates a greater turning effect (torque) that is transmitted to the smaller radius axle. This effectively multiplies the force, allowing a smaller input force on the wheel to exert a larger output force or torque on the axle.
Question 7: Which of the following describes the function of a pulley system?
- It changes the direction of the applied force and can also reduce the effort needed to lift a load (Correct answer)
- It only changes the direction of the applied force
- It increases the load
- It decreases the load
Correct answer: It changes the direction of the applied force and can also reduce the effort needed to lift a load
A pulley system can change the direction of the applied force, making it easier to pull down to lift an object up. Additionally, a system of multiple pulleys (a block and tackle) increases the mechanical advantage by distributing the load over several ropes. This reduces the amount of effort force required to lift a heavy load, though it requires pulling the rope a greater distance.
Free IST Mechanical Aptitude Questions and Answers
Which type of simple machine is a seesaw?