Newton’s Second Law in Rotational Form AP Physics 1 MCQ – Exam Style Questions etc.
Newton’s Second Law in Rotational Form AP Physics 1 MCQ
Unit 5: Torque and Rotational Dynamics
Weightage : 10-15%
Exam Style Practice Questions, Newton's Second Law in Rotational Form AP Physics 1 MCQ
Question
Two blocks are joined by a light string that passes over the pulley shown above, which has radius R and moment of inertia I about its center. T1 and T2 are the tensions in the string on either side of the pulley and α is the angular acceleration of the pulley. Which of the following equations best describes the pulley’s rotational motion during the time the blocks accelerate?
(A) m2gR = Iα (B) T2R = Iα (C) (T2 – T1)R = Iα (D) (m2 – m1)gR = Iα
Answer/Explanation
Ans:C
\(\sum \)τ = T2R – T1R = Iα
Questions
A solid cylinder of mass m and radius R has a string wound around it. A person holding the string pulls it vertically upward, as shown above, such that the cylinder is suspended in midair for a brief time interval Δt and its center of mass does not move. The tension in the string is T, and the rotational inertia of the cylinder about its axis is \(\frac{1}{2}MR^{2}\)
Question(a)
the net force on the cylinder during the time interval Δt is
(A) mg (B) T – mgR (C) mgR – Τ (D) zero
Answer/Explanation
Ans:D
Solution: If the cylinder is “suspended in mid air” (i.e. the linear acceleration is zero) then \(\sum f = 0\)