mec 5 point

8/11/2019 mec 5 point

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1.

The ball has a mass of 20 kg and a speed of v = 30

m/s at the instant it is at its lowest point.

Determine the tension in the cord at this instant.

a. 2196 N

b. 1796 N

c. 1596 N

d. 1996 N

2.

The beam shown in the figure is 5 inches wide and

10 inches deep. What is the maximum bending

stress?

a. 7721.0 psi

b. 2888.1 psi

c. 5500.3 psi

d. 3420.9 psi

3.

The frictional effects of the air on the

blades of the standing fan creates a couple

moment of Mo = 6 N-m on the blades. The

value of couple forces at the base of the

fan so that the resultant couple moment

on the fan is zero is

a. 80N

b. 40N

c. 20N

d. 1.8N

4.

The speed of block A if block B has an upward

velocity of 6 ft/s is

a. 12 ft/s ↑

b. 2 ft/s ↓

c. 1.5 ft/s ↑

d. 18 ft/s ↓

8/11/2019 mec 5 point


8/11/2019 mec 5 point


10.

A 2.5 in. diameter shaft is 2 ft. long. Its maximum shear stress is 10, 000 psi. What is the angular

deflection in degrees?

a. 0.96o

b. 0.45o

c. 0.78o

d. 0.56o

11.

Two men are just able to lift a 300 kg weight with a crowbar when the fulcrum for the lever is

0.3 m from the weight. The first

man exerts his strength at 0.9 m

while the second is at 1.5 m from

the fulcrum respectively. If the men

interchanged positions, they can

ralse a 340 kg weight. What force

does the first man exert?

a. 60 kg

b. 40 kg

c. 50 kg

d. 55 kg

12.

A 10 g blocks slides with a velocity of 20 cm/s on a

smooth level surface and makes a head on collision

with a 30 gram block moving in the opposite

direction with a velocity of 10 cm/s. If the collision is

perfectly elastic, what is the velocity of the 30-gram

block after the collision?

a. 5 cm/s

b. 15 cm/s

c. 10 cm/s

d. 25 cm/s

13.

If the cable has a tension of 3 N, determine the

acceleration of block B.

a. 4.26 m/s2 ↑

b. 8.31 m/s2 ↑

c. 4.26 m/s2 ↓

d. 8.31 m/s2 ↓

8/11/2019 mec 5 point


14.

What weight in pounds can

be lifted by a screw that has

an efficiency or 80% if it is

operated by a 50 lb force at

the end of a 30 inched lever

and the pitch of the screw is

1/2 inch?

a. 15, 500

b. 10, 000

c. 15, 000

d. 12, 000

15.

The y-component of the100N force is

a. 100N sin45o cos 60o

b. 100N cos45o cos 60o

c. 100N sin45o sin 60o

d. 100N cos45o sin 60o

16.

At a given instant, blocks A and B have the motion shown. The

acceleration of block B with respect to A is

a. 3i m/s

b. -1i m/s

c. 1i m/s

d. None of these

17.

If the magnitude of F is 80N, a = 60o and y = 45o, the

magnitude of its component is

a. Fx = 80.0N, Fy = 80.0N, Fz = 58.6N

b. Fx = 40.0N, Fy = 80.0N, Fz = 58.6N

c. Fy = 40.0N, Fz = 56.6N, Fx = 40.0N

d. Fx = 138.6N, Fy = 80.0N, Fz = 58.6N

18.

Determine the moment of

inertia of the T-section as

shown about its centroidal

axis parallel to the base.

a. 11092.12

b. 10094.31

c. 13091.42

d. 12098.12

8/11/2019 mec 5 point


19.

A man dropped a stone

into a well. Four

seconds later the

sound of a water splash

is heard. Assuming

sound travels at a

speed of 330 m/s,

determine how deep is

the well?

a. 67.12 m

b. 69.32 m

c. 68.89 m

d. 70.34 m

20.

Given the a - t graph. If v = 6m/s when t = 0, calculate the time t needed to stop the particle.

a. 3s

b. 16s

c. 6s

d. 12s

21.

A car tire is 30 inches in diameter. How fast in rpm does the wheel turns on the axle when the

automobile maintains a speed of 30 mph?

a. 368 rpm

b. 336 rpm

c. 315 rpm

d. 305 rpm

22.

A 10 Kg block rests on a smooth surface. If the

pulleys are massless and frictionless, the block's

initial acceleration is

a. 19.81 m/s2

b. 19.60 m/s2

c. 9.81 m/s2

d. 10.00 m/s2

23.

If expressed in Cartesian vector form, F1 is

a. (2.17 i + 3.75 j + 4.33 k) kN

b. (4.33 i + 3.75 j + 2.17 k) kN

c. (2.50 i + 3.54 j + 2.50 k) kN

d. (4.33 i + 3.54 j + 4.33 k) kN

8/11/2019 mec 5 point


24.

The position vector r is represented by

a. (3i + 4j) m

b. (-2i - 4j - 3k) m

c. (2i + 4j + 4k) m

d. (4j + 3k) m

25.

What is the maximum stress of the structure shown

a. 1300 psi

b. 1200 psi

c. 1400 psi

d. 1000 psi

26.

Determine the abscissa of the

centroid for the shadded area as

shown.

a. 4.5

b. 4.8

c. 2.5

d. 3.5

27.

The 10 Kg block is released from rest at A.

Select the equation that represents the

reduced form of the conservation of energy

theorem, necessary to determine the

maximum compression h in the spring at B.

Place the datum at A.

a. 0 = -98.1h + 50h2

b. 0 = -98.1h - 98.1 - 50h2

c. 0 = -98.1 - 50h2

d. 0 = -98.1 - 98.1h +50h2

28.

A solid shaft 2.0 m long is transmitting

27 kN-m torque. If the shear modulus

of the shaft material is 85 Gpa and the

allowable shearing stress is 70 Mpa,

determine the angle of twist between

the two ends of the shaft.

. a. 1.52o

b. 1.02o

c. 1.32o

d. 1.44o

8/11/2019 mec 5 point


29.

A 19-foot beam 10 inches

wide and 20 inches high

supports 1500 lb/ft on two

supports 14 feet apart. The

right end of the beam

extends 2 feet past the support. What is the

shearing stress midway between supports?

a. 1.0 psi

b. 67 psi

c. 2.0 psi

d. 10 psi

30.

What is the particle's position at the end

of 4s?

a. 10m

b. 30m

c. 40m

d. 20m

31.

A ball is thrown horizontally from A with a speed of vA= 6m/s as shown. If it strikes the ground

in t = 1s. The value of R is

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mec 5 point