SIFT Mechanical Comprehension 2

Question 1

What type of simple machine is a bottle opener?

Accepted Answer

Lever

Answer

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.

Question 2

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?

Accepted Answer

10 N

Answer

Total mass = 15 kg. Acceleration a = F/m_total = 30/15 = 2 m/s². Tension = m_B × a = 5 × 2 = 10 N.

Question 3

Which material has the highest thermal conductivity (transmits heat best)?

Accepted Answer

Copper

Answer

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).

Question 4

What is 'mechanical advantage' of a single fixed pulley?

Accepted Answer

1

Answer

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.

Question 5

If both ends of a horizontal pipe carry equal and opposite compressive forces, the pipe is under what type of stress?

Accepted Answer

Compression

Answer

When forces push inward from both ends, the pipe is compressed — it is under compressive stress, which tends to shorten or buckle the material.

SIFT Exam Practice Test

SIFT Exam Practice Test

SIFT Mechanical Comprehension 2