Engineering Fundamentals: An Introduction to Engineering, 4th ed.c

Problems 297

10.41.When learning to play some sports, such as tennis, golf,

or baseball, often you are told to follow through with

your swing. Using Equation (10.31), explain why

follow-through is important.

10.42.In many applications, calibrated springs are commonly

used to measure the magnitude of a force. Investigate

how typical force-measuring devices work. Write a

brief report to discuss your findings.

10.43.Calculate the moment created by the forces shown in

the accompanying figure about pointO.

10.44.We have used an experimental setup similar to

Example 10.1 to determine the value of a spring con-

stant. The deflection caused by the corresponding

weights are given in the accompanying table. What is

the value of the spring constant?

5 in.

O

70 lb

80 lb

5 in.

45

30

Problem 10.43

Problem 10.47

The Deflection of

Weight (lb) the Spring (in.)

5.0 0.48

10.0 1.00

15.0 1.90

20.0 2.95

10.47.Given that the three bars shown in the accompanying

figure are made of the same material, comparing bar

(a) to bar (b) which bar will stretch more, when sub-

jected to the same force F? Bar (a) and (b) have the

same cross-sectional area but different length. Com-

paring bar (a) to bar (c) having the same length but dif-

ferent cross-sectional areas, which bar will stretch

more? Explain.

10.45.If an astronaut and her space suit weight 250 lb on

Earth, what should be the volume of her suit if she is

to practice for weightless conditions in an underwater

neutral buoyant simulator, similar to the one used by

NASA as shown in Chapter 7?

10.46.Calculate the work required to bench press a 200-lb

weight, at a distance of 20 in.

F

(a)

(b)

(c)

F

F

10.48.Create a table that shows the relative magnitudes of

modulus of elasticity of steel to aluminum alloys, cop-

per alloys, titanium alloys, rubber, and wood.

10.49.Consider the parallel springs shown in the accompany-

ing figure. Realizing that the deflection of each spring

in parallel is the same and the applied force must equal

the sum of forces in individual springs, show that for

springs in parallel the equivalent spring constant Keis

KeK 1 K 2 K 3

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