Engineering Mechanics - KOP: Force and Acceleration

Exercise :: KOP: Force and Acceleration - General Questions

  • KOP: Force and Acceleration - General Questions
11. 

The pendulum bob B has a weight of 5 lb and is released from rest in the position shown, =0°. Determine the tension in string BC just after the bob is released, = 0°, and also at the instant the bob reaches point D, = 45°.

A. T0 = 0, T45 = 10.61 lb
B. T0 = 0.1551 lb, T45 = 10.61 lb
C. T0 = 0, T45 = 7.07 lb
D. T0 = 0.1551 lb, T45 = 7.07 lb

Answer: Option A

Explanation:

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12. 

A truck T has a weight of 8,000 lb and is traveling along a portion of a road defined by the lemniscate r2 = 0.2(106) cos 2 , where r is measured in feet and is in radians. If the truck maintains a constant speed of vr = 4 ft/s, determine the magnitude of the resultant frictional force which must be exerted by all the wheels to maintain the motion when = 0.

A. F = 29.2 lb
B. F = 859 lb
C. F = 87.5 lb
D. F = 26.7 lb

Answer: Option D

Explanation:

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13. 

A smooth can C, having a mass of 2 kg, is lifted from a feed at A to a ramp at B by a forked rotating rod. If the rod maintains a constant angular motion of = 0.5 rad/s, determine the force which the rod exerts on the can at the instant = 30°. Neglect the effects of friction in the calculation. The ramp from A to B is circular, having a radius of 700 min.

A. F = 19.62 N
B. F = 11.33 N
C. F = 10.63 N
D. F = 12.03 N

Answer: Option B

Explanation:

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14. 

The spool, which has a weight of 2lb, slides along the smooth horizontal spiral rod, r = (2) ft, where is in radians. If its angular rate of rotation is constant and equals = 4 rad/s, determine the tangential force P needed to cause the motion and the normal force that the spool exerts on the rod at the instant = 90°.

A. P = 0.499 lb, N = 5.03 lb
B. P = 5.50 lb, N = 15.65 lb
C. P = 3.35 lb, N = 2.43 lb
D. P = 1.677 lb, N = 4.77 lb

Answer: Option D

Explanation:

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15. 

Each of the three barges has a mass of 30 Mg, whereas the tugboat has a mass of 12 Mg. As the barges are being pulled forward with a constant velocity of 4 m/s, the tugboat must overcome the frictional resistance of the water, which is 2 kN for each barge and 1.5 kN for the tugboat. If the cable between A and B breaks, determine the acceleration of the tugboat.

A. a = 0.1667 m/s2
B. a = 0.1042 m/s2
C. a = 0.0278 m/s2
D. a = 0.01961 m/s2

Answer: Option C

Explanation:

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