Mechanical Aptitude Mechanical Aptitude Forces and Motion Principles 2 — Questions and Answers
Question 1: A 10 kg box is pushed across a frictionless surface with a net force of 20 N. What is its acceleration?
- 1 m/s²
- 2 m/s² (Correct answer)
- 5 m/s²
- 10 m/s²
Correct answer: 2 m/s²
Newton's second law: a = F/m = 20 N ÷ 10 kg = 2 m/s².
Question 2: Which of the following best describes inertia?
- The force that causes objects to accelerate
- The tendency of an object to resist changes in its state of motion (Correct answer)
- The energy stored in a moving object
- The friction between two surfaces
Correct answer: The tendency of an object to resist changes in its state of motion
Inertia is the property of matter that resists any change in velocity, whether at rest or in motion.
Question 3: A car traveling at 60 mph applies its brakes and comes to a stop in 6 seconds. What is the deceleration?
- 5 mph/s
- 10 mph/s (Correct answer)
- 15 mph/s
- 20 mph/s
Correct answer: 10 mph/s
Deceleration = change in speed ÷ time = 60 mph ÷ 6 s = 10 mph/s.
Question 4: When two equal and opposite forces act on a stationary object, the object will:
- Accelerate to the right
- Accelerate to the left
- Remain stationary (Correct answer)
- Rotate in place
Correct answer: Remain stationary
Equal and opposite forces produce a net force of zero, so the object remains in equilibrium.
Question 5: A ball is thrown horizontally from a cliff. Which statement about its motion is correct?
- It moves only horizontally
- Its horizontal speed decreases as it falls
- Its vertical speed increases due to gravity (Correct answer)
- It travels in a straight diagonal line
Correct answer: Its vertical speed increases due to gravity
Gravity continuously accelerates the ball downward, so vertical speed increases while horizontal speed remains constant.
Question 6: If you double the mass of an object while keeping the net force the same, the acceleration will:
- Double
- Stay the same
- Halve (Correct answer)
- Quadruple
Correct answer: Halve
From a = F/m, doubling mass with constant force cuts acceleration in half.
Question 7: A 5 kg object is in free fall (ignoring air resistance). What is the net force acting on it? (g = 10 m/s²)
- 0 N
- 5 N
- 50 N (Correct answer)
- 500 N
Correct answer: 50 N
Net force in free fall equals the weight: F = mg = 5 kg × 10 m/s² = 50 N.
Mechanical Aptitude Mechanical Aptitude Forces and Motion Principles 2
A 10 kg box is pushed across a frictionless surface with a net force of 20 N.
What is its acceleration?