EIT Dynamics and Vibrations 2

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)

Accepted Answer

4.04 s

Answer

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?

Accepted Answer

50 m/s²

Answer

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?

Accepted Answer

100 mph west

Answer

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?

Accepted Answer

150 m

Answer

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?

Accepted Answer

3.14 rad/s²

Answer

ω_f = 120 × (2π/60) = 4π rad/s; α = (4π − 0)/4 = π ≈ 3.14 rad/s².

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