Handouts
LINK: Engineering Mechanics Statics and Dynamics
Topics:
Newton’s Law of Motion
Conditions for Static Equilibrium
Friction Analysis of Flexible Cables
Properties of Sections
Dynamics
Kinematics
Kinetics
Motion at Constant Acceleration
Free Falling Bodies
Projectile Circular Motion
Exercises
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1. Bombs from a plane drops at a rate of one per second. Calculate the vertical distance between two bombs after the first had dropped for 8 seconds. Assume free falling body with g=9.81 m/s2. a. 75.4 m b. 81.3 m c. 72.8 m d. 78.5 m 2. Two cars A and B accelerate from a stationary start. The acceleration of A is 5 ft/s2 and that of B is 7 ft/s2. If B was originally 25 ft behind A, how long will it take B to overtake A? a. 8 sec b. 7 sec c. 6 sec d. 5 sec 3. A flywheel is brought to rest up to a speed of 850 rpm in 1 minute. What is the average angular acceleration until the wheel stops? a. -2.32 rad/sec2 b. -3.21 rad/sec2 c. -4.91 rad/sec2 d. -1.48 rad/sec2 4. A car travels 120 miles to city A in 3.8 hours and then travels 220 miles to city B in 5 hours. What is the average speed of the car for the trip? a. 35.28 mph b. 37.79 mph c. 39.22 mph d. 32.34 mph 5. A train with a top speed of 55 mph cannot accelerate or decelerate faster than 6 ft/s2. What is the minimum distance between two train stops in order for the train to be able to reach its top speed? a. 1084.52 ft b. 1133.62 ft c. 932.52 ft d. 1273.11 ft 6. A ball is thrown vertically upward with an initial speed of 68 ft/s. How long will it take for the ball to return to the thrower? a. 3.76 sec b. 4.22 sec c. 5.51 sec d. 6.01 sec 7. A ball is dropped from a height of 90 m above the ground. How long does it take to hit the ground? a. 5.62 sec b. 3.88 c. 4.28 sec d. 2.32 sec 8. A bicycle moves with a constant deceleration of -4 ft/s2. If the initial velocity of the bike was 15 ft/s, how far does it travel in 2.6 seconds? a. 20.3 ft b. 22.7 ft c. 25.5 ft d. 27.1 ft 9. If a car traveling at 67 mph suddenly locks its brakes and skids 387.4 ft, how long will it take for the car to come to complete stop? a. 6.1 sec b. 8.2 sec c. 7.9 sec d. 9.3 sec 10. A stone is dropped over a cliff and falls for 18 seconds before reaching the bottom. How high above the bottom is the cliff? a. 1589.2 m b. 1722.1 m c. 1821.4 m d. 1333.2 sec 11. What is the acceleration of a body that increases in velocity from 26 m/s to 58 m/s in 12 seconds? a. 2.67 m/s2 b. 3.28 m/s2 c. 4.44 m/s2 d. 1.28 m/s2 12. Six weights of 28, 22, 48, 25, 14 and 34 lbs hang in one plane from a horizontal support at distances 3, 4, 6, 7, 10, 13 ft, respectively, from the wall. What single force would replace these six weights? a. 5.32 ft b. 4.26 ft c. 6.92 ft d. 7.17 ft 13. Determine the single force that will replace the following coplanar forces: 122 N, 32o; 210 N, 112o; 166 N, 250o and 74 N, 310o. a. 32.5 N b. 28.6 N c. 45.2 N d. 49.2 N 14. A girder weighing 17,000 lbs is suspended by a cable 110 ft long. What horizontal pull is necessary to hold it 9 ft from the vertical position? a. 1395.6 lbs b. 1488.8 lbs c. 1213.3 lbs d. 1522.8 lbs 15. A 22 kg mass is suspended by a rope. What is the tension in the rope? a. 322.25 N b. 245.25 N c. 452.28 N d. 188.81 N 16. A 75.4 kg block needs 221.6 N to move horizontally. Find the friction between the block and the plane. a. 0.4 b. 0.5 c. 0.3 d. 0.2 17. A 55 lb block is placed in a horizontal plane with coefficient of friction of 0.18. Find the force needed to move the block horizontally. a. 38.2 N b. 44.2 N c. 48.3 N d. 35.8 N 18. Two forces 18 kg and 62 kg are acting at right angles. Find the resultant force. a. 52.3 kg b. 60.2 kg c. 64.6 kg d. 68.3 kg 19. Two forces are acting in the following direction: F1=120 kg at 34o and F2=88 kg at 128o. Find the resultant force. a. 133.2 kg b. 148.2 kg c. 158.8 kg d. 143.8 kg 20. A shot is fired at an angle of 50 deg with the horizontal at velocity of 320 fps. Calculate to the nearest, the range of projectile. a. 1524.9 yd b. 1438.3 yd c. 1683.8 yd d. 1043.9 yd 21. A ball is thrown from a tower 45 m high above the ground with a velocity of 250 m/s directed 25 deg from horizontal. How long until the ball hit the ground. a. 25.3 sec b. 21.1 sec c. 28.3 sec d. 18.9 sec 22. A 50 kg block resting on a 20 deg inclined plane from the horizontal, has a coefficient of friction of 0.60. Find the force parallel to the inclined that must be applied to cause impending motion down the plane. Use g=9.81 m/s2. a. 108.8 N b. 115.2 N c. 128.3 N d. 138.7 N 23. A 30 kg box is released from rest and travel down from a 30 deg inclined plane. If the coefficient of friction is 0.28, what will be the velocity of the box when it travels 15 m from its initial position? a. 6.28 m/s b. 7.84 m/s c. 8.71 m/s d. 5.33 m/s 24. A 120 kg box is dragged 85 m down the sidewalk at constant velocity. What work is done if the coefficient of the sliding friction between the box and the pavement is 0.28? a. 28 kJ b. 32 kJ c. 25 kJ d. 20 kJ 25. A truck weighing 5 kips moves a slope of 25 deg. What is the force generated by the engine if the truck is accelerating at a rate of 8 ft/sec2? Assume f=0.12. a. 2511.3 lbs b. 2687.8 lbs c. 2438.1 lbs d. 2811.5 lbs 26. A man weighs himself in an elevator. When the elevator is at rest, he weighs 160 lbs; when the elevator starts moving upwards he weighs 210 lbs. How fast is the elevator accelerating, assuming constant acceleration? a. 9 ft/sec2 b. 10 ft/sec2 c. 11 ft/sec2 d. 12 ft/sec2 27. An elevator weighing 4300 lbs attain an upward velocity of 25 fps in 8 sec with uniform acceleration. The tension in the supporting cable is _____. a. 4050.22 lbs b. 4717.31 lbs c. 4830.18 lbs d. 4322.76 lbs 28. A force of 50 N causes an acceleration of 3 m/s2 when acting on an 8 kg mass. What is the frictional force also acting? a. 26 N b. 24 N c. 28 N d. 30 N 29. How much does a 55 lb object weight on the moon (gmoon = 5.32 ft/sec2)? a. 7.09 lbs b. 8.30 lbs c. 10.32 lbs d. 9.09 lbs 30. What force is acting if a 85 slugs object accelerates at 10 ft/sec2? a. 800 lb b. 750 lb c. 850 lb d. 900 lb |
Forces in Equilibrium
| Forces in Equilibrium |
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A 10 kg weight is suspended by a cable from a ceiling. If a horizontal force of 5.8 kgs is applied to the weight, the cable will make an angle with the vertical equal to ____? SOLUTION: |
Rectiliner Motion
| Rectiliner Motion |
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Two cars are travelling at the same speed of 80 kph in the same direction on the level road with car A 100 meters ahead of car B. Car A slows down to make a turn, decelerating at 2.13 m/s2. In how many seconds will car B overtake car A. SOLUTION: |
Free Falling Bodies
| Free Falling Bodies |
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A ball is dropped down a well and six second later, the sound of the splash is heard. If the velocity of sound is estimated at 330 m/s, what is approximate depth of this well? SOLUTION: |
Projectile Motion
| Projectile Motion |
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A ball is thrown so that it is just clears a fence 12 ft high and 50 ft away. If it left the thrower’s hand 5 ft above the ground and at an angle of 60 degrees with the horizontal. What was the initial velocity of the ball in ft/sec? Neglecting air resistance. SOLUTION: |
