Ultimate Questions and Answers Flashcards

A gear train has a 20-tooth input gear, a 40-tooth idler gear, and a 60-tooth output gear. What is the overall gear ratio?

Answer: 1:3

The idler gear does not affect the gear ratio. The overall ratio is output teeth / input teeth = 60/20 = 3:1 (or input:output = 1:3). The 40-tooth idler only changes the rotation direction of the output.

A hydraulic press has an input piston area of 5 cm² and an output piston area of 100 cm². If the input force is 200N, what force is produced at the output?

Answer: 4,000N

By Pascal's principle, pressure is equal: P = F₁/A₁ = F₂/A₂. Therefore F₂ = F₁ × (A₂/A₁) = 200N × (100/5) = 200 × 20 = 4,000N.

A 500 kg load is lifted 4 meters using a pulley system with 80% efficiency. How much work input is required?

Answer: 24,500 J

Useful work output = mgh = 500 × 9.8 × 4 = 19,600 J. With 80% efficiency: Work input = Output / Efficiency = 19,600 / 0.80 = 24,500 J.

Two springs with spring constants k₁ = 200 N/m and k₂ = 300 N/m are connected in parallel. What is the combined spring constant?

Answer: 500 N/m

For springs in parallel, the combined spring constant is the sum: k_total = k₁ + k₂ = 200 + 300 = 500 N/m. Parallel springs share the load and are stiffer together.

An engine produces 150 kW of power. How much work does it perform in 30 seconds?

Answer: 4,500,000 J

Power = Work / Time, so Work = Power × Time = 150,000 W × 30 s = 4,500,000 J (or 4.5 MJ). Remember that 1 kW = 1,000 W and 1 W = 1 J/s.

A beam supported at both ends carries a 600N point load at its center. What is the reaction force at each support?

Answer: 300N each

For a simply supported beam with a centered point load, each support carries half the load due to symmetry. Reaction at each end = 600N / 2 = 300N. The upward forces (300N + 300N) equal the downward force (600N), satisfying equilibrium.