SIFT Mechanical Comprehension 3

Question 1

An object requires 300 J of work to move 15 meters. What is the average force applied?

Accepted Answer

20 N

Answer

Work = Force × Distance, so Force = Work / Distance = 300 / 15 = 20 N.

Question 2

A ball is thrown vertically upward. At the peak of its trajectory, what is its velocity?

Accepted Answer

Zero

Answer

At the highest point, the ball has momentarily stopped moving upward before gravity pulls it back down. Its instantaneous velocity is zero at the peak.

Question 3

What does a 'circuit breaker' do in an electrical system?

Accepted Answer

Automatically interrupts current flow when it exceeds a safe limit

Answer

A circuit breaker is an automatic switch that trips (opens the circuit) when current exceeds a safe level, preventing wires and components from overheating and causing fires.

Question 4

What type of stress does a bolt in a bolted joint primarily experience when the joint resists forces that try to slide the two halves sideways?

Accepted Answer

Shear stress

Answer

When two joined surfaces try to slide sideways past each other, the bolt resists this by being sheared (cut) along its cross-section — this is shear stress.

Question 5

What is the relationship between wavelength and frequency in a wave?

Accepted Answer

Wavelength and frequency are inversely proportional at constant wave speed

Answer

For a wave at constant speed: v = fλ. If speed is constant and frequency increases, wavelength must decrease proportionally, and vice versa.

SIFT Exam Practice Test

SIFT Exam Practice Test

SIFT Mechanical Comprehension 3