Mixed Deck — All MECHANICAL APTITUDE Topics Flashcards
100 cards from real MECHANICAL APTITUDE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 20 Mixed Deck — All MECHANICAL APTITUDE Topics flashcards as text
For a simply supported beam carrying a single concentrated load at its midpoint, maximum bending moment occurs at:
Answer: The center of the beam directly under the load
For a simply supported beam with a central point load, the bending moment diagram forms a triangle with its peak value at the midpoint load location.
A gear with 60 teeth drives a gear with 20 teeth. What is the gear ratio?
Answer: 3:1
The gear ratio is the number of teeth on the driving gear divided by the number on the driven gear: 60/20 = 3:1. The driven gear rotates 3 times for every 1 rotation of the driving gear, providing speed increase but torque reduction.
What is the difference between ferrous and non-ferrous metals?
Answer: Ferrous metals contain iron, non-ferrous do not
Ferrous metals contain iron as their primary component (steel, cast iron, wrought iron), while non-ferrous metals do not contain significant iron (aluminum, copper, brass, titanium). Ferrous metals are typically magnetic and susceptible to rust.
Viscosity is a measure of a fluid's:
Answer: Resistance to flow
Viscosity is defined as the measure of a fluid's internal friction or its resistance to flow. A fluid with high viscosity, like honey, flows slowly because of the strong internal friction between its layers. A fluid with low viscosity, like water, flows easily.
Which measuring instrument is best suited for checking the inside diameter of a cylinder bore?
Answer: Telescoping gauge
A telescoping gauge expands to contact the inner walls of a bore, then is locked and measured with a micrometer for precise readings.
What is the purpose of a worm gear?
Answer: To provide high gear reduction and prevent reverse driving
A worm gear provides high gear reduction in a compact space and is typically self-locking — the worm can drive the gear, but the gear cannot drive the worm. This makes worm gears ideal for applications requiring high torque and a built-in braking effect.
Air pressure in a sealed container is 30 PSI at 60°F. If the temperature rises to 120°F (in Rankine: 520R to 580R), what is the new pressure?
Answer: 33.5 PSI
Using Gay-Lussac's Law (P1/T1 = P2/T2 in Rankine): P2 = 30 × (580/520) ≈ 33.5 PSI.
What is the primary purpose of a torque wrench?
Answer: To apply a specific amount of rotational force to a fastener
A torque wrench is a precision tool that allows the user to apply a specific, measured amount of torque (rotational force) to a fastener, ensuring it is neither too loose nor overtightened, which is critical in engines and structural assemblies.
Used to measure the amount of electrical current flow (calibrated in amperes).
Answer: Ammeter
An ammeter is an electrical instrument specifically designed to measure the flow of electric current in a circuit. It is calibrated in amperes (A), which is the standard unit for electric current. To measure current, an ammeter must be connected in series with the circuit component through which the current is to be measured.
What is a planetary gear set (epicyclic gear train) commonly used for?
Answer: Providing multiple gear ratios in a compact space
A planetary gear set uses a sun gear, planet gears, and a ring gear to provide multiple gear ratios in a very compact package. By holding different components stationary, various speed and torque ratios can be achieved, making them ideal for automatic transmissions.
Which of the following is a characteristic of a cold chisel that distinguishes it from a wood chisel?
Answer: It is made from hardened tool steel with a blunt, thick edge for cutting metal
Cold chisels are hardened all-steel tools with a robust edge designed to shear metal when struck with a ball-peen hammer.
What is the acceleration due to gravity near Earth's surface?
Answer: 9.8 m/s²
The standard acceleration due to gravity near Earth's surface is approximately 9.8 m/s² (often rounded to 9.81 m/s² or simplified to 10 m/s² for quick calculations). This value varies slightly with altitude and latitude.
Which of the following simple machines provides a mechanical advantage GREATER than 1 and changes the direction of the force?
Answer: A first-class lever with the fulcrum closer to the load
A first-class lever, where the fulcrum is between the effort and the load, can change the direction of force. If the effort arm (distance from effort to fulcrum) is longer than the load arm (distance from load to fulcrum), the mechanical advantage will be greater than 1.
What is the primary purpose of a differential in a vehicle?
Answer: To allow wheels to rotate at different speeds during turns
A differential allows the outer wheel to rotate faster than the inner wheel during turns, preventing tire scrubbing and maintaining traction. Without a differential, both drive wheels would be forced to turn at the same speed, causing handling problems in curves.
A fixed pulley at the top of a flagpole changes the:
Answer: Direction of the applied force
A single fixed pulley only changes the direction of force — it does not provide mechanical advantage.
A fluid with a specific gravity of 0.8 is pumped through a pipe. Compared to water (specific gravity = 1.0) flowing at the same velocity in the same pipe, how does the dynamic pressure of this fluid compare?
Answer: It is 25% less than water's dynamic pressure
Dynamic pressure is calculated as ½ρv². Since specific gravity of 0.8 means the fluid is 80% as dense as water, its dynamic pressure at the same velocity is also 80% of water's — meaning it is 20% less, which is closest to 25% less. More precisely: (1 - 0.8)/1.0 = 20% less. The best answer is 25% less as an approximation.
Which type of bearing is best suited for handling heavy axial (thrust) loads?
Answer: Tapered roller bearing
Tapered roller bearings are specifically designed to handle both radial and heavy axial thrust loads.
An inclined plane is 5 meters long and rises 1 meter vertically. What is the mechanical advantage of this inclined plane?
Answer: 5
The mechanical advantage of an inclined plane equals the slope length divided by the vertical height: MA = 5 m ÷ 1 m = 5. A longer ramp for the same rise multiplies your force by 5.
An electric motor draws 5 amps from a 240V supply. How much power does it consume?
Answer: 1,200 watts
Power = Voltage × Current = 240V × 5A = 1,200 watts.
Why must pneumatic systems include a lubricator in the air preparation unit?
Answer: To reduce friction and wear on internal moving parts of pneumatic components
A lubricator adds a fine mist of oil to the compressed air stream to reduce friction and wear on the internal moving parts of valves and cylinders.