Material and density Flashcards
What is a linear and non-linear relationship
between two quantities?
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.
What is meant by a directly proportional
relationship between two quantities?
If a graph is plotted and the line of best fit is straight and goes through the origin then there is a
directly proportional relationship between the two quantities.
What is the spring constant?
The spring constant is the amount of force needed to stretch (or compress) a material by 1 m. Its unit is N/m.
How do you determine spring constant from
a force extension graph?
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.
What is the relationship between force,
spring constant, and extension?
Force = spring constant × extension
F = ke
Force (Newtons, N), Spring constant (Newtons per metre, N/m), Extension (metres, m)
What is Hooke’s law?
The extension of a material is directly proportional to the force applied up to the limit of proportionality (elastic limit).
On a force extension graph where is the limit
of proportionality?
The limit of proportionality on this graph is where the line stops being straight. It is the point at
which it begins to curve.
What is meant by elastic deformation?
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.
What is meant by inelastic deformation?
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.
How do you carry out a force extension
experiment accurately?
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.
What is the relationship between mass,
volume, and density?
Density =mass/volume
ρ =m/V
Density (kilograms per metre cubed, kg/m3), Mass (kilograms, kg), Volume (metres cubed
, m3)
How do you measure the volume of regular
shaped objects accurately?
The volume of a regular cuboid shaped object can be found by multiplying the width, length, and
height together. Each dimension can be found accurately by repeating the measurement with a ruler
in different places along each side (and then averaging) and ensuring the ruler is at 900 to the edge.
How do you measure the volume of
irregular shaped objects accurately?
Either:
Add a specific amount of water into a measuring cylinder. Add the irregular object to the water and measure
the new combined volume of the water and object. Subtract the volume of the water to get the volume of the
object.
or
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.
How do you measure the mass of
an object accurately?
Place a digital balance on a flat surface and zero it (press the tare button) before placing the object on it.
What do we mean by “uncertainty”
in a measurement?
Uncertainty is the range of values in which we expect the true value of a measurement to lie.
When a measurement is repeated,
what is the uncertainty in that
measurement?
When measurements are repeated the uncertainty in the measurement is 1⁄2 of the range. The range can be
found by taking the minimum value from the maximum
Why does density change when a
substance changes state?
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.
What do we mean by the resolution
of a measuring instrument?
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.
properties and particles of a solid
Properties of a solid:
- have a definite shape
- do not flow
- virtually impossible to compress
- expand if heated but usually less than a gas or liquid
Particles in a solid:
- strongly bonded together
- vibrate a little but not much compared to liquids or gases
- vibrate faster when heated
properties and particles of a liquid
Properties of a liquid:
- no definite shape
- can flow to take the shape of the bottom of a container
- very difficult to compress (virtually incompressible)
Particles of a liquid:
- weakly bonded together
- break their bonds easily
- vibrate and move more than those in a solid
- move faster when heated
properties and particles of a gas
Properties of a gas:
- no fixed shape
- gases spread (or diffuse) to completely fill a container
- gases are easily compressed
Particles of a gas;
- are “free” having no bonds between them
- have much more energy than those of a solid or liquid
- fly around, bouncing off each other and the walls of their container
