Mechanical Comprehension Flashcards
6 cards from real SIFT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Mechanical Comprehension flashcards as text
What type of simple machine is a bottle opener?
Answer: Lever
A bottle opener is a first-class lever: the fulcrum is between the effort and resistance. The cap edge is the fulcrum, the handle is the effort arm, and the bottle cap is the resistance.
Two blocks, A (10 kg) and B (5 kg), rest on a frictionless surface connected by a string. If a 30 N force is applied to block A, what is the tension in the string?
Answer: 10 N
Total mass = 15 kg. Acceleration a = F/m_total = 30/15 = 2 m/s². Tension = m_B × a = 5 × 2 = 10 N.
Which material has the highest thermal conductivity (transmits heat best)?
Answer: Copper
Copper is an excellent thermal conductor, which is why it is used in heat sinks, cooking pans, and electrical wiring. Wood, glass, and rubber are much poorer conductors (good insulators).
What is 'mechanical advantage' of a single fixed pulley?
Answer: 1
A single fixed pulley only changes the direction of force, not its magnitude. Its mechanical advantage is 1 — you pull with the same force as the load weight.
If both ends of a horizontal pipe carry equal and opposite compressive forces, the pipe is under what type of stress?
Answer: Compression
When forces push inward from both ends, the pipe is compressed — it is under compressive stress, which tends to shorten or buckle the material.
Water is flowing through a pipe. If the pipe splits into two equal branches, what happens to the flow speed in each branch (assuming incompressible flow)?
Answer: Flow speed halves in each branch
By the continuity equation (A₁V₁ = A₂V₂ + A₃V₃), when a pipe splits into two equal pipes, the total flow area doubles, so flow speed must halve to maintain the same volumetric flow rate.