NCEES Dynamics 3

Question 1

What is the coefficient of restitution (e) for a perfectly plastic (perfectly inelastic) collision?

Accepted Answer

0

Answer

A perfectly plastic collision has e = 0, meaning the objects stick together with no rebound velocity.

Question 2

A spring with k = 500 N/m is compressed 0.1 m. What is the elastic potential energy stored?

Accepted Answer

2.5 J

Answer

PE = ½kx² = ½ × 500 × 0.01 = 2.5 J.

Question 3

A particle moves along a path defined by x = 3t² and y = 4t. What is the speed at t = 2 s?

Accepted Answer

√(148) ≈ 12.17 m/s

Answer

vx = 6t = 12 m/s, vy = 4 m/s at t=2; speed = √(144+16) = √160 ≈ 12.65 m/s — closest to option A among the choices provided.

Question 4

An object of mass 4 kg is moving at 10 m/s. What is its kinetic energy?

Accepted Answer

200 J

Answer

KE = ½mv² = ½ × 4 × 100 = 200 J.

Question 5

For a rigid body rotating about a fixed axis, the relationship between tangential acceleration (at), angular acceleration (α), and radius (r) is:

Accepted Answer

at = α·r

Answer

Tangential acceleration equals angular acceleration times the radius, at = α·r.

NCEES Practice Test