Set 24
Problem 1 (ME October 1997)
A 10-lbm object is acted upon by a 40-lb force. What is the acceleration in ft/min2?
A. 8.0 x 10 to the 4th power ft/min2 C. 7.8 x 10 to the 4th power ft/min2
B. 9.2 x 10 to the 4th power ft/min2 D.
4.638 x 10 to the 4th power ft/min2 Problem 2
What horizontal force P can be applied to a 100-kg block in a level surface with
coefficient of friction of 0.2, that will cause and acceleration of 2.50 m/s2?
A. 343.5 N C. 106
N
B. 224.5 N D.
446.2 N Problem 3
A skier wishes to build a rope tow to pull her up a ski hill that is inclined at 15o with the horizontal. Calculate the tension needed to give the skier’s 54-kg body an
acceleration of 1.2 m/s2. Neglect friction.
A. 202 N C. 106
N
B. 403 N D. 304
N
Problem 4 (ME April 1997)
A pick-up truck is traveling forward at 25 m/s. The truck bed is loaded with boxes, whose coefficient of friction with the bed is 0.4. What is the shortest time that the truck can be brought to a stop such that the boxes do not shift?
A. 4.75 sec C. 5.45 sec
B. 2.35 sec D. 6.37
sec
Problem 5 (CE November 1996)
A 40-kg block is resting on an inclined plane making an angle of 20o from the horizontal.
If the coefficient of friction is 0.60, determine the force parallel to the incline that must be applied to cause impending motion down the plane. Use g = 9.81 m/s.
A. 77 C. 72
B. 82 D. 87
Problem 6 (ECE November 1997)
A 50-kilogram block of wood rest on the top of the plane whose length is 3 m. and whose altitude is 0.8 m. How long will it take for the block to slide to the bottom of the plane when released?
A. 1.51 seconds C. 2.51 seconds
B. 2.41 seconds D. 2.14
seconds
Problem 7 (CE May 1999)
A body weighs 40 lbs. starts from rest and inclined on a plane at an angle of 30o from the horizontal for which the coefficient of friction How long will it move during the third second?
A. 19.99 ft C.
18.33 ft
B. 39.63 ft D.
34.81 ft Problem 8
A car and its load weigh 27 kN and the center of gravity is 600 mm from the ground and midway between the front and rear wheel which are 3 m apart. The car is brought to rest from a speed of 54 kph in 5 seconds by means of the brakes. Compute the normal force on each of the front wheels of the car.
A. 7.576 kN C.
5.478 kN
B. 9.541 kN D. 6
kN
Problem 9 (ME April 1998, CE November 1999 “Structural”)
An elevator weighing 2,000 lb attains an upward velocity of 16 fps in 4 sec with uniform acceleration. What is the tension in the supporting cables?
A. 1,950 lb C.
2495 lb
B. 2,150 lb D.
2,250 lb
Problem 10 (CE November 1997
“Structural”)
A block weighing 200 N rests on a plane inclined upwards to the right at a slope of 4 vertical to 3 horizontal. The block is
connected to a cable initially parallel to the plane, passing through the pulley and connected to another block weighing 100 N moving vertically downward. The
coefficient of kinetic friction between the 200 N block and the inclined plane is 0.10.
Which of the following most nearly gives the acceleration of the system?
A. a = 2.93 m/sec2 C. a = 1.57 m/sec2
B. a = 0.37 m/sec2 D. a = 3.74 m/sec2
Problem 11 (ME October 1997) A car travels on the horizontal unbanked circular track of radius r. Coefficient of friction between the tires and the track is 0.3. If the car’s velocity is 10 m/s, what is the smallest radius it may travel without skidding?
A. 50 m C. 15
m
B. 60 m D. 34
m Problem 12
If a car travels at 15 m/s and the track is banked 5o, what is the smallest radius it can travel so that friction will not be necessary to resist sliding?
A. 262.16 m C.
278.14 m
B. 651.23 m D.
214.74 m
Problem 13 (CE May 1999)
A vertical bar of length L with a mass of 40 kg is rotated vertically about its one end at 40 rpm. Find the length of the bar if it makes an angle of 45o with the vertical?
A. 1.58 m C. 3.26
m
B. 2.38 m D. 1.86
m Problem 14
The seats of a carousel are attached to a vertical rotating shaft by a flexible cable 8 m long. The seats have a mass of 75 kg. What is the maximum angle of tilt for the seats if the carousel operates at 12 rpm?
A. 30o C. 45o
B. 35o D. 39o
Problem 15 (CE November 1998) A highway curve is super elevated at 7o. Find the radius of the curve if there is no lateral pressure on the wheels of a car at a speed of 40 mph.
A. 247.4 m C.
229.6 m
B. 265.6 m D.
285.3 m
Problem 16 (CE November 1997
“Structural”)
A 2-N weight is swung in a vertical circle of 1-m radius at the end of the cable that will break if the tension exceeds 500 N. Find the angular velocity of the weight when the cable breaks:
A. 49.4 rad/s C. 24.9
rad/s
B. 37.2 rad/s D. 58.3
rad/s
Problem 17 (ME April 1998)
Traffic travels at 65 mi/hr around a banked highway curve with a radius of 3000 ft.
What banking angle is necessary such that
friction will not be required to resist the centrifugal force?
A. 5.4o C. 3.2o
B. 18o D. 2.5o
Problem 18 (ME April 1997)
A concrete highway curve with a radius of 500 feet is banked to give a lateral pressure equivalent to f = 0.15. For what coefficient of friction will skidding impend for a speed of 60 mph?
A. < 0.360 C. >
0.310
B. < 0.310 D. >
0.360
Problem 19 (ME October 1997)
A 3500 lbf car is towing a 500 lbf trailer.
The coefficient of friction between all tires and the road is 0.80. How fast can the car and trailer travel around an unbanked curve of radius 0.12 mile without either the car or trailer skidding?
A. 87 mph C. 26
mph
B. 72 mph D. 55
mph
Problem 20 (ME October 1997) A cast-iron governor ball 3 inches in diameter has its center 18 inches from the point of support. Neglecting the weight of the arm itself, find the tension in the arm if the angle with the vertical axes is 60o.
A. 7.63 lb C. 7.56
lb
B. 6.36 lb D. 7.36
lb Problem 21
An object is placed 3 feet from the center of a horizontally rotating platform. The
coefficient of friction is 0.3. The object will begin to slide off when the platform speed is nearest to:
A. 17 rpm C. 22
rpm
B. 12 rpm D. 27
rpm
Problem 22 (ME April 1998)
A force of 200 lbf acts on a block at an angle of 28o with respect to horizontal. The block is pushed 2 feet horizontally. What is the work done by this force?
A. 320 J C. 480
J
B. 540 J D. 215
J
Problem 23 (ME April 1998)
A 10-kg block is raised vertically 3 meters.
What is the change in potential energy?
Answer in SI units closest to:
A. 350 N-m C. 350
kg-m2/s2
B. 294 J D. 320
J Problem 24
At her highest point, a girl on the swing is 7 feet above the ground, and at her lowest point, she is 3 feet above the ground. What is her maximum velocity?
A. 10 fps C. 14
fps
B. 12 fps D. 16
fps
Problem 25
An automobile has a power output of 1 hp.
When it pulls a cart with a force of 300 N, what is the cart’s velocity?
A. 249 m/s C. 2.49
m/s
B. 24.9 m/s D.
0.249 m/s Problem 26
A hunter fires a 50 gram bullet at a tiger.
The bullet left the gun with a speed of 600 m/s. What is the momentum of the bullet?
A. 15 kg-m/s C. 300
kg-m/s
B. 30 kg-m/s D. 150
kg-m/s Problem 27
An elevator can lift a load of 5000 N from the ground level to a height of 20 meters in 10 seconds. Find the horsepower rating of the elevator.
A. 10000 C. 13.4
B. 13400 D.
1340 Problem 28
The average horsepower required to raise a 150-kg box to a height of 20 meters over a period of one minute is:
A. 450 hp C.
2960 hp
B. 0.657 hp D. 785
hp
Problem 29
What is the force of attraction between two 90-kg bodies spaced 40 m apart? Assume gravitational constant, G = 6.67 x 10-11 N-m2/kg2
A. N C.
N
B. N D.
N Problem 30
What is the efficiency of the pulley system, which lifts a 1 tonne load, a distance of 2 m by the application of the force 150 kg for a distance of 15 m?
A. 11% C. 75%
B. 46% D.
89%
Problem 31
How much mass is converted to energy per day in a nuclear power plant operated at a level of 100 MW?
A. kg C.
kg
B. kg D.
kg
Problem 32 (ECE April 1998)
What is the kinetic energy of a 4000-lb automobile, which is moving at 44 ft/s?
A. ft-lb C.
ft-lb
B. ft-lb D.
ft-lb
Problem 33 (ME October 1997) A 4000-kg elevator starts from rest
accelerates uniformly to a constant speed of 2.0 m/s and decelerates uniformly to stop 20
m above its initial position. Neglecting the friction and other losses, what work was done on the elevator?
A. Joule C.
Joule
B. Joule D.
Joule Problem 34
The brakes of a 1000-kg automobile exert 3000 N. How long will it take for the car to come to a complete stop from a velocity of 30 m/s?
A. 15 sec C. 5
sec
B. 10 sec D. 2
sec
Problem 35 (ME April 1997)
A car weighing 40 tons is switched to a 2%
upgrade with a velocity of 30 mph. If the train resistance is 10 lbs/ton, how far does the grade will it go?
A. 1124 ft C.
1204 ft
B. 2104 ft D.
1402 ft
Problem 36 (ME October 1997)
A body weighing 1000 lbs. fall 6 inches and strikes a 2000 lbs (per inch) spring. What is the deformation of the spring?
A. 3 inches C. 100
mm
B. 6 inches D. 2
inches
Problem 37
A 16-gram mass is moving at 30 cm/s while a 4-gram mass is moving in an opposite direction at 50 cm/s. They collide head on and stick together. Their velocity after collision is:
A. 14 cm/s C. 13
cm/s
B. 15 cm/s D. 18
cm/s Problem 38
A 5-kg rifle fires a 15-g bullet at a muzzle velocity of 600 m/s. What is the recoil velocity of the rifle?
A. 1800 m/s C. 18
m/s
B. 180 m/s D. 1.80
m/s Problem 39
A 0.50-kg ball with a speed of 20 m/s strikes and sticks to a 70-kg block resting on a frictionless surface. Find the block’s velocity.
A. 142 m/s C. 1.42
m/s
B. 14.2 m/s D.
0.142 m/s