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°.

1

S9

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°.

2

S9

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.

3

S9

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.

4

S9

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.

5

S9

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.

6

S9

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.

7

S9

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.

8

Purchase answer to see full

attachment