PROPERTIES OF MATERIALS

Question 1

Define density.

Answer 1

Mass per unit volume.

Question 2

Define spring constant.

Answer 2

A measure of the stiffness of a particular sample.

Question 3

State Hookes Law.

Answer 3

Force is directly proportional to extension up to the limit of proportionality.
F = k🔺️L

Question 4

Define Elastic Deformation.

Answer 4

When a material returns to its original length when the force stretching it is removed.

Question 5

Define Plastic Deformation.

Answer 5

When a material does not return to is original length when force stretching it is removed. Material said to have had a permanent change in length.

Question 6

Define Elastic Limit.

Answer 6

The maximum force that can be applied to a material without causing permanent extension.

Question 7

Define Limit of Proportionality.

Answer 7

Limit beyond where the curve no longer obeys Hookes Law.

Question 8

Describe Springs in Series.

Answer 8

Force the same in each spring.
Extensions add up.
1/Kt = 1/K1 + 1/K2

Question 9

Describe Springs in Parallel.

Answer 9

Forces add up.
Extension of each spring the same.
Kt = K1 + K2

Question 10

Formulas for energy stored.

Answer 10

E = ½F🔺️L
E = ½k🔺️L²

Question 11

Define Tensile Stress.

Answer 11

Force applied per unit cross sectional area.

Question 12

Define Tensile Strain.

Answer 12

Extension produced per unit length.

Question 13

Define Young Modulus.

Answer 13

Tensile stress per unit Tensile Strain up to the limit of proportionality.
A measure of stiffness of a material.
YM = FL / A🔺️L

Question 14

Define Yield Point.

Answer 14

Point where wire suddenly drops when wire subjected to increasing strain.

Question 15

Define UTS/Breaking Stress.

Answer 15

Maximum Tensile stress material can withstand before it breaks.

Question 16

Define Stiffness.

Answer 16

Measure of how difficult it is to change shape or size of a material.

Question 17

Define Brittle.

Answer 17

Material breaks without any plastic Deformation.

Question 18

Define Strength.

Answer 18

Measure of stress required to break a material.

Question 19

Define Strong.

Answer 19

Requires large stress to break (high UTS).

Question 20

Define Weak.

Answer 20

Requires small stress to break (small UTS).

Question 21

Define Ductile.

Answer 21

Material can be drawn into a wire. Shows extended plastic deformation + becomes elongated under tension.

Question 22

Define Tough.

Answer 22

Requires large amount of energy to break (large plastic deformation.)

Question 23

Define Elastic Strain Energy.

Answer 23

Potential energy stored in material that has been stretched.