All Prescribed Practicals Flashcards
What is an independent variable?
The variable you change during an experiment
What is a dependent variable?
The variable which changes depending on the independent variable
What is a control variable?
The variable which stays the same during an experiment
Which variable is plotted on the x axis (generally)
Independent
Which variable is plotted on the y axis (generally)
Dependent
Which variable is plotted on the y axis in investigations of hooke’s law?
What is it’s quantity?
- independent variable
- Force
(Remember the units in the equation is N = N/m x m)
Which variable is plotted on the x axis in investigations of hooke’s law?
What is it’s quantity?
- dependent variable
- extension - m
(Remember the units in the equation is N = N/m x m)
What is the equation for Hooke’s law?
F=kx
Force = spring constant x extension
N = N/m x m
In the equation y=mx +c, what is the dependent variable shown by? (Generally)
Y
In the equation y=mx +c, what is the independent variable shown by? (Generally)
X
What is the equation for moments?
What is the rule for moments
M = Fd
Moment = Force x perp length
CM = ACM
What is the relation between y and x if c = 0
(y=mx + c)
Directly proportional
What is the relation between y and x if c = 1
(y=mx + c)
Proportional
What are the properties of direct proportionality?
- straight line
- through origin
What is the property of proportionality?
A straight line
In the equation s = d/t, what is the relationship between speed and time?
Inversely proportional
How do you demonstrate direct proportionality on a graph when two values are inversely proportional?
- Have y value on the y axis
- have 1/x on the x axis
What shape is a graph of inverse proportionality?
A curve from top to bottom
Does an inversely proportional graph touch the axes?
No
What is the definition of moments
the product of a force and perpendicular distance from the fulcrum
State the principal of moments (2)
- for an object in rotational equilibrium
- ACM = CM about the same point
State Ohm’s law
Voltage is directly proportional to current at constant temperature
What is a systematic error?
An error which cannot be reduced by repeating
What is the unit for moments?
Nm or Ncm
What is the equation for Ohm’s law?
V=RI
What is the relationship between resistance and length?
What equation represents this?
- resistance is directly proportional to length of the wire
- R=kl
What is the unit for k in R=kl
Ohms per meter / ohms per centimetre
P1
Average speed depending on height of a ramp
Give apparatus (4) and the method (5) used.
- Apparatus:
- a ball bearing
- runway
- metre rule
- stopwatch
- Method:
- measure the length of the slope using a metre rule
- position the runway with the ball bearing at a vertical distance of 20cm from the desk
- release the ball bearing and measure the time taken for the ball to travel the length of the slope
- record results in a table
- repeat at different heights and calculate average speeds (s=d/t)
(Results should show average speed to be directly proportional to the height)
P2
Hooke’s law
Give apparatus (3) and the method (6) used.
- Apparatus:
- spring
- slotted masses
- a metre rule
- Method:
- measure the original length of the spring
- add a 100g mass (1N load) to the spring
- measure the new length of the spring
- calculate and record the extension
- increase mass and repeat
- record all results in a table
(Results should show that extension is proportional to load)
P3
Moments (in A)
P4
Investigate the relationship between the mass and volume of solids and liquids
Give apparatus (3) and the method (9) used.
Liquids:
- Apparatus:
- 100cm3 measuring cylinder
- electronic balance
- 250cm3 of water
- Method:
- measure the mass of the cylinder using the balance
- zero the balance
- pour 20 cm3 of water into the cylinder
- record its mass and volume in a table
- do the same with other volumes
- find density (p=m/v)
For solids:
- use a cube,
- using a ruler, measure it’s length breadth and heights to get volume,
- then get the mass and density
P5
Measure power by measuring the time taken to climb stairs
Give apparatus (3) and the method (7) used.
- Apparatus:
- bathroom scales
- a metre rule
- a stopwatch
- Method:
- measure the mass of the person
- use w=mg to get weight
- find the height of one step on the stairs using a metre rule
- count the number of steps and multiply by the height of a step. This is the height of the stairs
- use a stopwatch to measure time taken to go up the stairs
- repeat and get the average time to get up the stairs
- use w=fd and p=e/t to get power
P6
Refraction through a glass block, using angles to plot a graph of incidence against refraction
Give apparatus (6) and the method (8) used.
- Apparatus:
- rectangular glass block
- ray box
- protractor
- A4 page
- pencil
- ruler
- Method:
- place the block in the centre of the page and draw the outline in pencil
- draw a normal
- direct a light ray at the point where the normal strikes the block
- mark the paths of the incident and refracted rays using dots
- connect the dots and put a normal on the bottom ray
- connect the two rays
- measure the angles of incidence and refraction (protractor), then record in a table
- repeat at different angles of incidence
P7
Ohm’s law
(On A)
P8
Investigate the relationship between resistance and length
Give variables (3)
Variables:
- Indy: length of wire
- dep: resistance
- control: temp and cross sectional area of wire
P9
Investigating how magnetic field strength depends on:
- current in a coil,
- number of turns in a coil,
- material of the core
Essentially, for each construct an electromagnet and measure the number of iron nails it attracts over the same distance
You need:
- a variable resistor
- an ammeter
- a coil of copper wire
- a laminated soft iron core
- for material you need other materials for cores too
- a power supply
