OAR FREE OAR Mechanical Reasoning Question and Answers 2 — Questions and Answers
Question 1: A hydraulic press has a small piston with an area of 2 sq in and a large piston with an area of 20 sq in. If a force of 15 lb is applied to the small piston, what force is exerted by the large piston?
- 150 lb (Correct answer)
- 30 lb
- 300 lb
- 75 lb
Correct answer: 150 lb
By Pascal's principle, force is multiplied by the area ratio: 15 × (20/2) = 150 lb.
Question 2: Two meshing gears have 12 and 36 teeth respectively. If the smaller gear rotates at 900 RPM, what is the speed of the larger gear?
- 300 RPM (Correct answer)
- 2700 RPM
- 450 RPM
- 150 RPM
Correct answer: 300 RPM
Gear speed is inversely proportional to tooth count: 900 × (12/36) = 300 RPM.
Question 3: A 200-lb crate sits on a surface with a coefficient of static friction of 0.4. What minimum horizontal force is needed to start moving the crate?
- 80 lb (Correct answer)
- 40 lb
- 120 lb
- 200 lb
Correct answer: 80 lb
Static friction force equals the coefficient times the normal force: 0.4 × 200 = 80 lb.
Question 4: In a first-class lever, the fulcrum is located 2 ft from the load and 6 ft from the effort. If the load weighs 150 lb, what effort is required to balance it?
- 50 lb (Correct answer)
- 75 lb
- 450 lb
- 25 lb
Correct answer: 50 lb
By the lever principle, effort × effort arm = load × load arm, so effort = 150 × 2/6 = 50 lb.
Question 5: A block-and-tackle pulley system has 4 supporting ropes. Ignoring friction, what effort is needed to lift a 240-lb load?
- 60 lb (Correct answer)
- 120 lb
- 80 lb
- 240 lb
Correct answer: 60 lb
The mechanical advantage equals the number of supporting ropes, so effort = 240/4 = 60 lb.
Question 6: A spring with a constant of 30 lb/in is compressed 4 inches. How much potential energy is stored in the spring?
- 240 in-lb (Correct answer)
- 120 in-lb
- 60 in-lb
- 480 in-lb
Correct answer: 240 in-lb
Spring energy = ½kx² = ½ × 30 × 4² = 240 in-lb.
OAR FREE OAR Mechanical Reasoning Question and Answers 2
A hydraulic press has a small piston with an area of 2 sq in and a large piston with an area of 20 sq in.
If a force of 15 lb is applied to the small piston, what force is exerted by the large piston?