Mechanical Aptitude Mechanical Aptitude Forces and Motion Principles 5 â Questions and Answers
Question 1: A 500 kg car accelerates from 0 to 20 m/s in 10 seconds. What net force was applied?
- 250 N
- 500 N
- 1000 N (Correct answer)
- 2500 N
Correct answer: 1000 N
a = 20/10 = 2 m/s²; F = ma = 500 à 2 = 1000 N.
Question 2: Which of the following is an example of potential energy converting to kinetic energy?
- Pushing a stationary box
- A ball rolling to a stop due to friction
- A roller coaster descending a hill (Correct answer)
- Lifting a weight overhead
Correct answer: A roller coaster descending a hill
As the roller coaster descends, gravitational potential energy converts into kinetic energy (speed).
Question 3: A force is applied at an angle to the direction of motion. Which component does useful work?
- The component perpendicular to motion
- The component parallel to motion (Correct answer)
- The vertical component only
- All components equally
Correct answer: The component parallel to motion
Work = F à d à cos(Ξ), so only the component of force parallel to the displacement does work.
Question 4: If the speed of an object doubles, its kinetic energy:
- Doubles
- Triples
- Quadruples (Correct answer)
- Stays the same
Correct answer: Quadruples
KE = œmv², so doubling v increases KE by a factor of 2² = 4 (quadruples).
Question 5: A lever has a 3 m effort arm and a 1 m load arm. A 10 N effort is applied. What load can it lift?
- 3.3 N
- 10 N
- 30 N (Correct answer)
- 90 N
Correct answer: 30 N
Using the lever principle: effort à effort arm = load à load arm â 10 à 3 = load à 1, so load = 30 N.
Question 6: An object is in uniform circular motion. Which quantity remains constant?
- Velocity
- Acceleration direction
- Speed (Correct answer)
- Net force direction
Correct answer: Speed
In uniform circular motion, speed (magnitude) stays constant even though the direction of velocity constantly changes.
Question 7: Which scenario demonstrates the conservation of momentum?
- A ball slowing down due to air resistance
- Two carts colliding and sticking together on a frictionless track (Correct answer)
- A car accelerating with its engine
- A spring launching a ball upward
Correct answer: Two carts colliding and sticking together on a frictionless track
On a frictionless track with no external forces, the total momentum before and after collision is conserved.
Mechanical Aptitude Mechanical Aptitude Forces and Motion Principles 5
A 500 kg car accelerates from 0 to 20 m/s in 10 seconds.
What net force was applied?