Chapter 5: Forces and Matter

Question 1

stretched

Answer 1

tensile forces

Question 2

compressed

Answer 2

compressive forces

Question 3

bent

Answer 3

bending forces

Question 4

twisted

Answer 4

torsional forces

Question 5

load

Answer 5

the force (usually weight) stretches an object (a spring).

Question 6

change of spring with lead

Answer 6

-If the load is increased too far the spring becomes permanently stretched and will not return to its original length. It has been inelastically deformed.

Question 7

load extension graph

Answer 7

-at first, the graph slopes up steadily. This shows that the extension increases in equal steps as the load increases.
-Then the graph curves. This happens when the load is so great that the spring has become permanently damaged. It will not return to its original length.

Question 8

extension

Answer 8

the increased length of an object for eg a spring when a load for eg weight is attached to it.

Question 9

limit of proportionality

Answer 9

up to this limit, the extension on a spring is proportional to load

Question 10

after limit of proportionality

Answer 10

-if the spring is stretched beyond this point it will be permanently damaged. I the load is removed, te spring will not return all the way to its original, deformed length.

Question 11

hookes law

Answer 11

the extension of a spring is proportional tot he load applied to it provided the limit of proportionality is not exceeded.

Question 12

hookes law

Answer 12

F = kx

Question 13

spring constant

Answer 13

force / unit extension

Question 14

spring constant

Answer 14

the constant of proportionality the measure of the stiffness of a spring.
The bigger the load required to change its length and the steeper the gradient when the load is plotted against the extension (when the extension on the horizontal axis.

Question 15

how rubber behaves

Answer 15

-The graph obtained is not a straight line. Rather it has a slightly S-shaped curve. This shows that the extension is not exactly proportional to the load.
-Eventually increasing the load no longer produces any extension. The rubber feels very stiff. When the load is removed the graph does not come back exactly to zero.

Question 16

pressure of fluids

Answer 16

In fluid such as water pressure does not simply act downwards- it acts equally in all directions. This is because the molecules of the fluid move around in all directions causing pressure on every surface they collide with.

Question 17

pressure formula

Answer 17

force/area

Question 18

pressure

Answer 18

the force acting per unit area at right angles to a surface.

Question 19

pascal

Answer 19

the SI unit of pressure equivalent to one newton per square meter. 1 Pa = 1 N/m2 = 1Pa

Question 20

change in pressure

Answer 20

densityacceleration due to gravitydepth
p = pgh

Pressure p is proportional to depth height.
Pressure also depends on the density p of the material.