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
An object requires 300 J of work to move 15 meters. What is the average force applied?
Answer: 20 N
Work = Force × Distance, so Force = Work / Distance = 300 / 15 = 20 N.
A ball is thrown vertically upward. At the peak of its trajectory, what is its velocity?
Answer: Zero
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.
What does a 'circuit breaker' do in an electrical system?
Answer: Automatically interrupts current flow when it exceeds a safe limit
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.
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?
Answer: Shear stress
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.
What is the relationship between wavelength and frequency in a wave?
Answer: Wavelength and frequency are inversely proportional at constant wave speed
For a wave at constant speed: v = fλ. If speed is constant and frequency increases, wavelength must decrease proportionally, and vice versa.
A 60 W light bulb runs for 5 hours. How much electrical energy does it consume in kilowatt-hours?
Answer: 0.3 kWh
Energy = Power × Time = 60 W × 5 hr = 300 Wh = 0.3 kWh (divide by 1,000 to convert W to kW).