physics: matter and materials

Question 1

density

Answer 1

mass per unit volume

Question 2

pressure

Answer 2

the normal force acting per unit cross- sectional area

Question 3

change in pressure

Answer 3

density × acceleration due to gravity × depth

Question 4

Archimedes’ principle

Answer 4

the upthrust acting on a body is equal to the weight of the liquid or gas that it displaces

Question 5

extention

Answer 5

the increase in the length of a material from its original length

Question 6

spring constant

Answer 6

the force per unit extension for a spring

Question 7

Hook’s law

Answer 7

provided the elastic limit is not exceeded, the extension of a n object is proportional to the applied force

Question 8

elastic deformation

Answer 8

an object that returns to its initial length when the force is removed has deformed elastically

Question 9

plastic deformation

Answer 9

an object that does not return to its intial length when the force is removed is deformed permanently - it has deformed plastically

Question 10

limit of proportionality

Answer 10

the point beyond which extension is no longer proportional to the force

Question 11

elastic limit

Answer 11

the value of stress beyond which an object will not return to its original dimensions

Question 12

strain

Answer 12

extension per unit length

Question 13

stress

Answer 13

force per unit cross sectional area that acts at right angles to a surface

Question 14

young modulus

Answer 14

the stress in the material divided by the strain

Question 15

elastic potential energy or strain energy

Answer 15

energy stored in a body due to a change in its shape

Question 16

work done

Answer 16

the product of the force and the distance moved in the direction of the force; the area under a force - extension graph