NCEES Dynamics 2

Question 1

A 5 kg block slides down a frictionless incline at 30° to the horizontal. What is the acceleration of the block?

Accepted Answer

4.91 m/s²

Answer

Acceleration = g·sin(30°) = 9.81 × 0.5 = 4.91 m/s².

Question 2

A particle undergoes circular motion with radius 2 m and constant speed 6 m/s. What is its centripetal acceleration?

Accepted Answer

18 m/s²

Answer

Centripetal acceleration = v²/r = 36/2 = 18 m/s².

Question 3

A 10 kg object is acted upon by a net force of 50 N. What is the resulting acceleration?

Accepted Answer

5 m/s²

Answer

By Newton's second law, a = F/m = 50/10 = 5 m/s².

Question 4

Two masses, 3 kg and 7 kg, are connected by a string over a frictionless pulley (Atwood machine). What is the acceleration of the system?

Accepted Answer

3.92 m/s²

Answer

a = (m2−m1)g/(m1+m2) = (7−3)×9.81/10 = 3.92 m/s².

Question 5

A ball is thrown horizontally at 20 m/s from a 80 m high cliff. How long does it take to hit the ground?

Accepted Answer

4.04 s

Answer

Time = √(2h/g) = √(160/9.81) ≈ 4.04 s; horizontal velocity doesn't affect vertical fall time.

NCEES Practice Test