Mechanical Aptitude Mechanical Aptitude Forces and Motion Principles 4 — Questions and Answers
Question 1: A spring with a spring constant of 200 N/m is compressed by 0.05 m. What force does it exert?
- 0.25 N
- 4 N
- 10 N (Correct answer)
- 40 N
Correct answer: 10 N
Hooke's Law: F = kx = 200 N/m × 0.05 m = 10 N.
Question 2: When is the mechanical advantage of a simple machine greater than 1?
- When the output force is less than the input force
- When the output force equals the input force
- When the output force is greater than the input force (Correct answer)
- When there is no friction
Correct answer: When the output force is greater than the input force
Mechanical advantage > 1 means the machine multiplies force, so output force exceeds input force.
Question 3: A pendulum swings back and forth. At which point in its swing is kinetic energy greatest?
- At the highest point on either side
- Midway between the highest and lowest point
- At the lowest point of the swing (Correct answer)
- It is constant throughout
Correct answer: At the lowest point of the swing
Kinetic energy is maximum at the lowest point where potential energy is minimum and speed is greatest.
Question 4: Two ice skaters push off from each other. Skater A has twice the mass of Skater B. Which statement is true?
- Skater A moves faster
- Skater B moves faster (Correct answer)
- Both skaters move at the same speed
- Neither skater moves
Correct answer: Skater B moves faster
By conservation of momentum, the lighter Skater B receives the same force but has less mass, so it gains greater velocity.
Question 5: What is the unit of momentum?
- Joule (J)
- Newton (N)
- Kilogram-meter per second (kg·m/s) (Correct answer)
- Watt (W)
Correct answer: Kilogram-meter per second (kg·m/s)
Momentum = mass × velocity, so its unit is kg·m/s.
Question 6: A machine has an input force of 50 N and an output force of 150 N. What is its mechanical advantage?
- 0.33
- 1
- 3 (Correct answer)
- 7500
Correct answer: 3
Mechanical advantage = output force ÷ input force = 150 N ÷ 50 N = 3.
Question 7: Friction between two surfaces is generally higher when:
- The surfaces are smoother
- The normal force is greater (Correct answer)
- The object is moving faster
- The contact area is smaller
Correct answer: The normal force is greater
Friction force = μ × normal force, so greater normal force directly increases friction.
Mechanical Aptitude Mechanical Aptitude Forces and Motion Principles 4
A spring with a spring constant of 200 N/m is compressed by 0.05 m.
What force does it exert?