Mechanical Reasoning Principles Flashcards

A hydraulic jack has a small piston with a 1 sq-in area and a large piston with a 20 sq-in area. A 50 lb force on the small piston generates how much force on the large piston?

Answer: 1000 lb

Pascal's principle: force output = force input × (area output / area input) = 50 × 20 = 1000 lb.

A shaft transmits power through a V-belt to a driven pulley. If the driver pulley has a 4-inch diameter and spins at 1800 RPM, what is the RPM of a 12-inch driven pulley?

Answer: 600 RPM

Speed ratio = 4/12 = 1/3; driven RPM = 1800 × (1/3) = 600 RPM.

A cam converts which type of motion to another?

Answer: Rotary motion to linear (reciprocating) motion

A cam is a rotating or sliding piece that converts rotary motion into a follower's reciprocating or oscillating linear motion.

Which class of lever has the effort between the fulcrum and the load?

Answer: Class 3

In a Class 3 lever the effort is applied between the fulcrum and the load, as seen in a pair of tweezers.

A ratchet and pawl mechanism is used primarily to:

Answer: Allow rotation in one direction only

The pawl engages the ratchet teeth to permit rotation in one direction while preventing reverse rotation.

Two objects of identical size are dropped from the same height — one is solid steel, the other solid aluminum. Ignoring air resistance, which hits the ground first?

Answer: They hit at the same time

In the absence of air resistance, all objects fall with the same gravitational acceleration regardless of mass.

A pipe carrying compressed air develops a small crack. The air leaks outward rather than the outside air leaking in because of:

Answer: Higher pressure inside the pipe

Fluids flow from regions of higher pressure to lower pressure; the compressed air inside has higher pressure than the atmosphere outside.