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Unformatted text preview: ES 2120 Exam 1 September 21, 2009 1) Block A starts at rest and is accelerated to the left at 3 in/s2. Find: a) The velocity of B at any time t. b) The distance B will have traveled after 5 seconds. c) The relative velocity vector, VEIA at t = 5 seconds.
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mt WWW WW9 M vﬁ’t' V3 .130 Ck”: : «QB 2 3mg; (CQN$WNT} 20 points ES 2120 Exam 1 September 21, 2009 2) Pin A, which is attached to link AB, is constrained to move in a circular slot CD.
Knowing that at t = O the pin starts from rest and moves so that speed increases at a
constant rate of 20 mm/sz, Determine the magnitude of the total acceleration when a) t = 0 (Sketch Solution)
b) t = 2 seconds (Sketch Solution) Answers: 20 points
W lé’" ES 2120 Exam 1 September 21, 2009 3) A basketball player shoots the ball at the basket, which is 25 feet away, as shown. lf the
ball goes through the center of the basket, determine:
a) The required initial speed v0.
b) The angle (i) that the trajectory of the ball will make with vertical when the ball
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a. 463,23" 20 points ES 2120 Exam 1 September 21, 2009 4) A 3kg disk D is attached to the end of a cord as shown. The other end of the cord is attached at the center of the platform. Knowing the maximum tension in the cord is 100
N and the coefficient of kinetic friction between the disk and the platform is W = 0.1. If
the platform is rotating rapidly, and the disk is placed on it and released from rest.
Determine, at the time the cord breaks,: a) The tangential acceleration. b) The velocity. c) The time it took to break the cord.
(Include a free body diagram with your solution) Answers: mesm%:amsnazaaed T2: lOQ N
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EQQN ﬁ Mfg?” my QM wwg” 33 \lg‘mﬁ: \10) + Qkt WWW r 003% 20 points ES 2120 Exam 1 September 21, 2009 5) As the gear A rolls on the ﬁxed gear B, the point P on gear A can be described by the
equations r = 1 + cosnt and 6 = rct where r is measured in feet, 6 in radians, and t in seconds. When t = O, P is situated at PO as shown. When t = ‘A 5, determine the
magnitude and direction of the: a) Velocity of P.
b) Acceleration of P.
(Hint sketch your solution to determinethe direction) Answers: ﬁlms"
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 Spring '10
 Kobbe
 Dynamics, Acceleration, Velocity, .........

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