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## CVEN 202 University of The District of Columbia Engineering Mechanics Exam Engineering Mechanics II answer the following :……………………………

CVEN 202 University of The District of Columbia Engineering Mechanics Exam Engineering Mechanics II answer the following :………………………………. S9
UNIVERSITY OF THE DISTRICT OF COLUMBIA
School of Engineering and Applied Sciences
Civil Engineering
Spring 2020
Final Exam: CVEN-202/ Engineering Mechanics II
Date: 5/5/2020
NAME:____________________________________________________
1. The pendulum of the Charpy impact machine has a mass of 48 kg and a radius of
gyration of kA = 1.50 m. If it is released from rest when θ = 0°, determine its angular
velocity just before it strikes the specimen S, θ = 90°.
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2. The system consist of a 11-lb disk A, 6-lb slender rod BC, and a 2-lb smooth collar C. If
the disk rolls without slipping, determine the velocity of the collar at the instant θ = 24°.
The system is released from rest when θ = 59°.
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3. At the instant r = 2.0m, the 4-kg disk is given a speed of v = 1 m/s, perpendicular to the
elastic cord. Determine the speed of the disk and the rate of shortening of the elastic cord
at the instant r = 1.6 m. The disk slides on the smooth horizontal plane. Neglect its size.
The cord has an unstretched length of 1.3m.
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4. Pinion gear A rolls on the gear racks B and C. If B is moving to the right at 9 ft/s and C is
moving to the left at 2 ft/s, determine the angular velocity of the pinion gear and the
velocity of its center A.
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5. A 3-lb ball A is traveling horizontally at 15 ft/s when it strikes a 11-lb block B that is at
rest. If the coefficient of restitution between the plane and the block is e = 0.8 and the
coefficient of friction is µk = 0.42, determine the time for the block B to stop sliding.
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6. The 3-Mg car has a velocity of v1 = 163 km/h when the driver sees an obstacle in front of
the car. It takes 0.73 s for him to react and lock the brakes, causing the car to skid. If the
car stops when it has traveled a distance of 176 m, determine the coefficient of kinetic
friction between the tires and the road.
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7. The skateboard rider leaves the ramp at A with an initial velocity vA = 25 m/s at a 30°
angle. If he strikes the ground at B, determine the time of flight and the distance the
skateboard rider travels before landing on the ground at B.
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8. The train consists of a 30-Mg engine E, and cars A, B, and C, which have a mass of 36
Mg, 44 Mg, and 47 Mg, respectively. If the tracks provide a traction force of F=60kN on
the engine wheels, determine the speed of the train when t=28s, starting from an initial
speed of 19 m/s. Also, find the horizontal coupling force D between the engine E and car
A. Neglect rolling resistance.
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