physics - material and density

Question 1

What is a linear and non-linear relationships between two quantities?

Answer 1

• If a graph is plotted and the line of best fit is straight then we say that there is a linear relationship between the two quantities on the x and y axes.
• If the line is not straight then it is non-linear.

Question 2

What is meant by a directly proportional relationship between two quantities?

Answer 2

the line of best fit is straight and goes through the origin then there is a directly proportional relationship between the two quantities.

Question 3

What is the spring constant?

Answer 3

The spring constant is the amount of force needed to stretch (or compress) a material by 1 m.
- the unit is N/m

Question 4

How do you determine spring constant from a force extension graph?

Answer 4

The spring constant is the gradient of the straight part of a force-extension graph when force is on the y-axis and extension on the x-axis.

Question 5

What is the relationship between force, spring constant, and extension?

Answer 5

Force = spring constant × extension

Question 6

What is Hooke’s law?

Answer 6

The extension of a material is directly proportional to the force applied up to the limit of proportionality (elastic limit)

Question 7

On a force extension graph where is the limit of proportionality?

Answer 7

It is the point at
which it begins to curve.

Question 8

What is meant by elastic deformation?

Answer 8

An object which is stretched (or compressed) will return to its original length when the force is removed if it hasn’t passed the limit of proportionality.

Question 9

What is meant by inelastic deformation?

Answer 9

An object which is stretched (or compressed) will not return to its original length when the force is removed if it has passed the limit of proportionality. There will be permanent deformation.

Question 10

How do you carry out a force extension experiment accurately?

Answer 10

Set up a clamp stand with a spring. Clamp a ruler making sure it is vertical with a set square. Make sure the zero of the ruler is at the bottom of the spring. Add masses and record the extension of the ruler each time. Make sure to measure the extension at eye-level.

Question 11

What is the relationship between mass,
volume, and density?

Answer 11

Density = mass/volume

Question 12

How do you measure the volume of regular
shaped objects accurately?

Answer 12

width × length × height

Question 13

How do you measure the volume of irregular shaped objects accurately?

Answer 13

Fill a Eureka can to the spout with water. Add your irregular object to the water and allow the water to run into a measuring cylinder. The volume of the water displaced is the volume of the object.

Question 14

How do you measure the mass of an object accurately?

Answer 14

Place a digital balance on a flat surface and zero it before placing the object on it.

Question 15

What do we mean by “uncertainty” in a measurement?

Answer 15

Uncertainty is the range of values in which we expect the true value of a measurement to lie.

Question 16

When a measurement is repeated, what is the uncertainty in that
measurement?

Answer 16

When measurements are repeated the uncertainty in the measurement is 1⁄2 of the range.

Question 17

Properties of solids and their particles?

Answer 17

• have a definite shape
• do not flow
• strongly bonded to each other
• vibrate a little

Question 18

Properties of liquids and their particles?

Answer 18

• no definite shape
• can flow and take the shape of any container
• weakly bonded to each other
• virbate and moce more than a solid

Question 19

Properties of gas and their particles?

Answer 19

• no fixed shape
• gases spread to completely fill their container
• gases have no bonds between them
• bounce of each other and the walls of their container
• lots of energy

Question 20

How can particle arrangement be used to explain the differences in density between solids, liquids, and
gasses?

Answer 20

• If we consider the same volume of a substance in its solid, liquid and gaseous forms then there will be much
  more space between the particles in a gas than in a liquid or solid.
• same volume we would have much less mass of gas, density of a gas is less than a solid or liquid.

Question 21

Why does density change when a substance changes state?

Answer 21

When a substance changes state the same mass of substance will now occupy a different volume. Since density = mass/volume it follows that density will change since volume changes.

Question 22

What do we mean by the resolution of a measuring instrument?

Answer 22

The resolution of a measuring instrument is the smallest change that can be read from that instrument e.g. 1
mm on a ruler, or 1° on a protractor.