8/18/2019 ES 12 [1516B] CQ9 - Newton's 2nd Law (Rigid Bodies) (TH)

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ES 12 2

nd

 Semester AY 2015-2016 31 March 2016

Comprehensive Quiz No. 9

ewton’s 2

nd

 Law Rigid Bodies)

ES 12 3-31-16/CQ9

Name: Signature

Student No: Section: ES 12 TH General Instructions: Read and understand each situational problem given below. Put a box on your final answers. Show

clearly all pertinent solutions and state the assumptions made, if any.  Any form of intellectual dishonesty will be

strictly penalized. SUBMIT YOUR ANSWER SHEET ON OR BEFORE 12 NOON TOMORROW (April 1,

2016) to your respective lab instructor’s pigeon hole.  

On your answer sheet, write the following statement and affix your signature:

“I swear upon my honor that I did not give nor receive any inappropriate aid in this comprehensive quiz.”  

Problem 1

 The 30 kg pendulum has its mass center at G and a

radius of gyration about point G of  k G = 300 mm.

 The spring attached has a stiffness k = 300 N/m 

and is unstretched when θ = 0°. It is released from

rest when θ = 60°. At that instant,

a.) [30%] Draw the FBD = EFD of the pendulum.

Label all vectors and their respective directions

properly.

b.) [30%] Determine the angular acceleration of the

pendulum.

c.) [20%] Determine the reactions at O.

d.) [20%] Determine the acceleration of point A. 

Problem 2

 A spring with stiffness k = 20

N/m  is attached to the

geometric center C of a 50 kg

homogenous disk rolling on a

rough inclined surface(µs=0.20, µk =0.10) as shown.

 The radius of the disk is 0.2

m . The spring is unstreched

at Position 1 when a constant clockwise moment M = 15 N-m is applied to it. Consider

Position 2 when the disk is 0.6 m down the incline.

a.) [40%] Draw the FBD = EFD of the disk at Position 2. Label all vectors and their respective

directions properly.

b.) [40%] Determine whether the disk is rolling without slipping or not. (HINT: how much

friction is developed?)

c.) [20%] Determine the corresponding acceleration of point C.