09 Materials

Question 1

What is the definition of density?

Answer 1

Mass per unit volume.

Question 2

What is the equation of density?

Answer 2

Mass / volume (m/v)

Question 3

What is the unit for density?

Answer 3

Kg m^-3 or g cm^-3

Question 4

What is the symbol of density?

Answer 4

p

Question 5

What is the density of pure water?

Answer 5

1000kg m^-3

Question 6

What is the definition of precision?

Answer 6

The smallest non-zero reading that can be measured.

Question 7

What does the uncertainty have to be bigger than?

Answer 7

The instruments precision.

Question 8

When a quantity is found by raising another quantity to a power,how do you get the percentage uncertainty?

Answer 8

Multiply the percentage uncertainty of the original quantity by the power.
eg- d^3 —> %Ud x 3

Question 9

When a quantity in multiplied or divided by another, how do you find the combined percentage uncertainty?

Answer 9

Add the values together.

Question 10

If there is no range then what is the uncertainty?

Answer 10

The same as the precision

Question 11

What does vernier mean?

Answer 11

2 scales that cross

Question 12

How do you use a vernier micrometer?

Answer 12

•take a reading close to the jaws using the ratchet.
•read the main scale reading from the barrel and add this value to micrometer reading on the thimble where the 2 scales meet

Question 13

How do you use vernier callipers?

Answer 13

Start by looking at where the 0 on the bottom scale meets the other scale. This gives the mm’s. Then look at which line on the bottoms scale lines up perfectly with the main scale. This gives the 100th’s of a mm.

Question 14

What is this?

Answer 14

Digital callipers

Question 15

What is this?

Answer 15

A vernier micrometer.

Question 16

What is this?

Answer 16

Vernier callipers

Question 17

What is Hooke’s law?

Answer 17

Hooke’s law is obeyed if extension is directly proportional to the stretching force provided the limit of the proportionality has not been exceeded.

Question 18

What is the definition of spring constant?

Answer 18

The stretching force per unit extension.

Question 19

What is the symbol for spring constant?

Answer 19

k

Question 20

What is spring constant (k) measured in?

Answer 20

N m‐1.

Question 21

What error does a set square avoid?

Answer 21

Parallax error.

Question 22

What is the independent variable for the Hooke’s law practical?

Answer 22

The mass / force / weight.

Question 23

What is the dependent variable of the Hooke’s law practical?

Answer 23

Extension

Question 24

What is the control variable of the Hooke’s law practical?

Answer 24

Use the same spring.

Question 25

In the Hooke's law practical, how do you ensure that the ruler is vertical?

Answer 25

Use a **spirit level** or set square.

Question 26

What is a source of error in the Hooke's law experiment? *not parallax *

Answer 26

Masses aren't the correct mass

Question 27

As a spring stretches what happens to the force needed to stretch it?

Answer 27

It increases

Question 28

Where is elastic strain energy stored?

Answer 28

In a stretched string

Question 29

What is the area between the line and the extension axis equal to in a force vs extension graph?

Answer 29

The energy stored in a spring that has been stretched by an amount equal to ΔL

Question 30

What in tension in P + tension in Q equal to?

Answer 30

The weight

Question 31

What is the tension in each spring equal to?

Answer 31

½ weight

Question 32

What is the extension of each spring compared with if it was a single spring supporting the weight?

Answer 32

½

Question 33

What is the spring constant of a parallel combination of 2 identical springs?

Answer 33

Double that of a single spring.

Question 34

What is the tension of each spring equal to?

Answer 34

The weight

Question 35

What is the extension of each spring compared with if it was a single spring supporting the weight?

Answer 35

The same

Question 36

What is the extension of the combination compared to that if a single spring?

Answer 36

Double

Question 37

What is the spring constant of a series combination of two springs half of?

Answer 37

The spring constant of a single spring.

Question 38

What type of line on a force vs extension graph should a material which obeys hookes law produce?

Answer 38

A straight line through the origin.

Question 39

What happens to an elastic material after it has been stretched and the load has been removed?

Answer 39

It returns to its original length.

Question 40

What is a material which has a permanent stretch once the load has been removed said to have?

Answer 40

To have been stretched beyond its elastic limit and has shown plastic behaviour.

Question 41

What is the area between the loading curve and the extension axis equal to in a force vs extension graph?

Answer 41

The energy stored in the stretched material.

Question 42

What is the area between the unloading curve and the extension axis equal to in a force vs extension graph?

Answer 42

The energy used to lift the load each time a mass is removed from the hanger.

Question 43

What is the shaded area called?

Answer 43

A hysteresis loop

Question 44

What is the difference between the loading and the unloading areas equal to on a force vs extension graph?

Answer 44

The energy converted to heat in the rubber band during the experiment.