EIT Dynamics and Vibrations 2 — Questions and Answers
Question 1: A ball is launched horizontally from a 80 m cliff with a speed of 20 m/s. How long does it take to reach the ground? (g = 9.81 m/s²)
- 2.02 s
- 4.04 s (Correct answer)
- 3.19 s
- 5.72 s
Correct answer: 4.04 s
Using h = ½gt², t = √(2h/g) = √(160/9.81) ≈ 4.04 s.
Question 2: A particle travels in a circle of radius 2 m at a constant speed of 10 m/s. What is the centripetal acceleration?
- 5 m/s²
- 20 m/s²
- 50 m/s² (Correct answer)
- 100 m/s²
Correct answer: 50 m/s²
Centripetal acceleration a = v²/r = (10)²/2 = 50 m/s².
Question 3: Train A travels east at 60 mph and Train B travels west at 40 mph. What is the velocity of B relative to A?
- 20 mph east
- 100 mph east
- 20 mph west
- 100 mph west (Correct answer)
Correct answer: 100 mph west
v_B/A = v_B − v_A = −40 − 60 = −100 mph, meaning 100 mph westward.
Question 4: A car starts from rest and accelerates uniformly at 3 m/s². How far does it travel in 10 seconds?
- 30 m
- 75 m
- 150 m (Correct answer)
- 300 m
Correct answer: 150 m
Using s = ½at², s = ½(3)(10²) = 150 m.
Question 5: A flywheel starts from rest and reaches 120 rpm in 4 seconds. What is its angular acceleration?
- 1.57 rad/s²
- 3.14 rad/s² (Correct answer)
- 6.28 rad/s²
- 12.57 rad/s²
Correct answer: 3.14 rad/s²
ω_f = 120 × (2π/60) = 4π rad/s; α = (4π − 0)/4 = π ≈ 3.14 rad/s².
Question 6: A particle has a velocity vector v = 4i + 3j m/s. What is its speed?
- 3.5 m/s
- 5.0 m/s (Correct answer)
- 7.0 m/s
- 25.0 m/s
Correct answer: 5.0 m/s
Speed = |v| = √(4² + 3²) = √25 = 5.0 m/s.
Question 7: Gear A has 20 teeth and meshes with Gear B, which has 60 teeth. If Gear A spins at 300 rpm, what is the speed of Gear B?
- 50 rpm
- 100 rpm (Correct answer)
- 200 rpm
- 900 rpm
Correct answer: 100 rpm
N_A × T_A = N_B × T_B → N_B = 300 × (20/60) = 100 rpm.
EIT Dynamics and Vibrations 2
A ball is launched horizontally from a 80 m cliff with a speed of 20 m/s.
How long does it take to reach the ground? (g = 9.81 m/s²)