11 Materials

Question 1

density of a substance

Answer 1

mass per unit volume of the substance

D=m/v

Question 2

hooke’s law

Answer 2

the extension of a spring is proportional to the force needed to extend it
F=k∆L
(k= spring constant and stiffness )

Question 3

elastic limit

Answer 3

point beyond which a wire is permanently stretched

Question 4

elasticity

Answer 4

property of a solid that enables it to regain its shape after it has been deformed or distorted

Question 5

pascal

Answer 5

unit of pressure or tree equal to 1Nm-1

Question 6

stress

Answer 6

force per unit area of cross-section in a solid perpendicular to the cross-section
T/A

Question 7

strain

Answer 7

extension per unit length of solid when deformed

∆L/L

Question 8

young modulus

Answer 8

stress/ strain (assuming the limit of proportionality has not been exceeded)
TL / A ∆L

Question 9

yield point

Answer 9

ponit at which the tree in a wire suddenly drops when the wire is subjected to increasing strain

Question 10

elastic limit

Answer 10

point beyond which a wire is permanently stretched

Question 11

plastic deformation

Answer 11

deformation of a solid beyond its elastic limit

Question 12

ultimate tensile stress

Answer 12

tensile stress needed to break a solid material

Question 13

breaking stress

Answer 13

tensile stress needed to break a solid material

Question 14

brittle

Answer 14

snaps without stretching or bending subject to stress

Question 15

ductile

Answer 15

stretches easily without breaking

Question 16

limit of proportionality

Answer 16

the military beyond which, when a wire or a spring is stretched, its extension is no longer proportional to force that stretches it

Question 17

measure the density of a solid

Answer 17

• measure mass

- calculate dimension and then the volume (sphere radius = 4/3 π r^3)

Question 18

measure the density of a liquid

Answer 18

• measure mass

- measure the volume in measuring cylinder

Question 19

measure the density of a irregular solid

Answer 19

• measure the mass
• measure the amount of water it displaces
• D=m/v

Question 20

density of alloys

Answer 20

add the two density together

Question 21

springs in parallel

Answer 21

spring constant

K= Kp + Kq

Question 22

springs in series

Answer 22

spring constant

1/K = 1/Kp + 1/Kq

Question 23

energy stored in a stretched spring

Answer 23

Ep=1/2 F∆L = 1/2 K∆L^2

Question 24

elastic energy stores in a stretched wire

Answer 24

1/2 T ∆L

area under force - extension graph

Question 25

Elastic strain energy

Answer 25

Up to the elastic limit of a sample, all the work done in stretching it is stored potential energy, or Elastic Strain Energy