Stress, Strain, Tension, Compression, Elasticity

ANSWER ALL QUESTION ON A SEPARATE SHEET OF PAPER 4 COLUMN FORMAT

2

2

Force

of elasticity =

Strain Area

change in dimension

= Degree of Deformation =

orginal dimension

in Pa (unit of Pressure) 1 Pa = 1 N/m

Area = r = (

Stress

Modulus Stress

Strain

Measured

π π

=

2

D

) **** You NEED THIS FOR #2 and #4

2

1. The heels on a pair of women’s shoes have a radius of .5 cm at the bottom. If 30% of the weight of a woman 480N is

supported by each heel, find the stress on each heel. Stress = Force/area

2. Find the diameter of an 18 m(L) long steel wire that will stretch no more than .009 m(ΔL) when a load (stress) of 3800

N is hung on the end of the wire. The Young’s Modulus for steel wire is 200 x 10

9

N/m

2

.

Stress

Strain

F L

Y

A

L

•

= =

• Δ

3. For safety in climbing mountaineers use a nylon rope that is 50 m long(L) and .01 m in diameter. When supporting a

900 N climber the rope stretches 1.6 m (ΔL) under tension. Find the Young’s Modulus(Y) for the nylon rope

Stress

Strain

F L

Y

A

L

•

= =

• Δ

Stress, Strain, Tension, Compression, Elasticity

ANSWER ALL QUESTION ON A SEPARATE SHEET OF PAPER 4 COLUMN FORMAT

4. The elastic limit of steel is 5.0 Pa (N/m

2

), find the minimum diameter a steel wire can to support a 700 N weight

without exceeding its elastic limit.

Force

Maximum Stress =

Minimum Area

5. The distortion of the earth’s crust is an example of sheer on a large scale. A particular rock has a sheer modulus of 1.5

x10

10

Pa(N/m

2

)(Shear Modulus, S). What shear stress is applied when a 10 km layer (h) of rock is sheared a distance

of 5 m (Δx).

6. Human bone has a Young’s Modulus of 14.5 x10

8

N/m

2

(Y). Under compression, it can withstand a stress of about 160

x 10

6

N/m

2

(stress) before breaking. Assuming a human adult thigh bone (femur) is about .5 m (L) long, how much

compression (ΔL) can the bone withstand before breaking.

F

F L

A

Y

L

A

L

L

•

= =

Δ

•Δ

Strain

F

Shear Stress F h

A

S

x

Shear A x

h

•

= = =

Δ

• Δ

Stress, Strain, Tension, Compression, Elasticity

ANSWER ALL QUESTION ON A SEPARATE SHEET OF PAPER 4 COLUMN FORMAT

7. A cylindrical aluminum pillar 7.00 high has a radius of 30.0 cm. If a 2000-kg sculpture is placed on top of the pillar,

by how much is the pillar compressed?

8. A mass of 2.00 kg is supported by a copper wire of length 4.00 m and diameter 4.00 mm. Determine (a) the stress in

the wire and (b) the elongation of the wire.

9. A uniform pressure of 5.00 × 10

4

Pa is exerted on a copper block having a volume of 10

–3

m

3

. What is the change in

volume of the block?

10. During a tensile strength experiment, a small-diameter fiber is elongated by a force of 0.0250 N. The fiber has an

initial length of 0.200 m and stretches a distance of 4.00 × 10

24

m. The Young’s modulus for the material being tested

is 7.60 × 10

10

Pa. Determine the diameter of the fiber.

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