All Prescribed Practicals

Question 1

What is an independent variable?

Answer 1

The variable you change during an experiment

Question 2

What is a dependent variable?

Answer 2

The variable which changes depending on the independent variable

Question 3

What is a control variable?

Answer 3

The variable which stays the same during an experiment

Question 4

Which variable is plotted on the x axis (generally)

Answer 4

Independent

Question 5

Which variable is plotted on the y axis (generally)

Answer 5

Dependent

Question 6

Which variable is plotted on the y axis in investigations of hooke’s law?

What is it’s quantity?

Answer 6

• independent variable
• Force

(Remember the units in the equation is N = N/m x m)

Question 7

Which variable is plotted on the x axis in investigations of hooke’s law?

What is it’s quantity?

Answer 7

• dependent variable
• extension - m

(Remember the units in the equation is N = N/m x m)

Question 8

What is the equation for Hooke’s law?

Answer 8

F=kx

Force = spring constant x extension
N = N/m x m

Question 9

In the equation y=mx +c, what is the dependent variable shown by? (Generally)

Answer 9

Y

Question 10

In the equation y=mx +c, what is the independent variable shown by? (Generally)

Answer 10

X

Question 11

What is the equation for moments?

What is the rule for moments

Answer 11

M = Fd
Moment = Force x perp length

CM = ACM

Question 12

What is the relation between y and x if c = 0

(y=mx + c)

Answer 12

Directly proportional

Question 13

What is the relation between y and x if c = 1

(y=mx + c)

Answer 13

Proportional

Question 14

What are the properties of direct proportionality?

Answer 14

• straight line
• through origin

Question 15

What is the property of proportionality?

Answer 15

A straight line

Question 16

In the equation s = d/t, what is the relationship between speed and time?

Answer 16

Inversely proportional

Question 17

How do you demonstrate direct proportionality on a graph when two values are inversely proportional?

Answer 17

• Have y value on the y axis
• have 1/x on the x axis

Question 18

What shape is a graph of inverse proportionality?

Answer 18

A curve from top to bottom

Question 19

Does an inversely proportional graph touch the axes?

Answer 19

No

Question 20

What is the definition of moments

Answer 20

the product of a force and perpendicular distance from the fulcrum

Question 21

State the principal of moments (2)

Answer 21

• for an object in rotational equilibrium
• ACM = CM about the same point

Question 22

State Ohm’s law

Answer 22

Voltage is directly proportional to current at constant temperature

Question 23

What is a systematic error?

Answer 23

An error which cannot be reduced by repeating

Question 24

What is the unit for moments?

Answer 24

Nm or Ncm

Question 25

What is the **equation** for **Ohm’s law**?

Answer 25

V=RI

Question 26

What is the relationship between **resistance and length**? What **equation** represents this?

Answer 26

- resistance is directly proportional to length of the wire - R=kl

Question 27

What is the **unit** for **k** in R=kl

Answer 27

Ohms per meter / ohms per centimetre

Question 28

P1 Average speed depending on height of a ramp Give **apparatus** (**4**) and the **method** (**5**) used.

Answer 28

1. Apparatus: - a ball bearing - runway - metre rule - stopwatch 2. 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)

Question 29

P2 Hooke’s law Give **apparatus** (**3**) and the **method** (**6**) used.

Answer 29

1. Apparatus: - spring - slotted masses - a metre rule 2. 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)

Question 30

P3 Moments (in A)

Question 31

P4 Investigate the relationship between the mass and volume of solids and liquids Give **apparatus** (**3**) and the **method** (**9**) used.

Answer 31

Liquids: 1. Apparatus: - 100cm³ measuring cylinder - electronic balance - 250cm³ of water 2. 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

Question 32

P5 Measure power by measuring the time taken to climb stairs Give **apparatus** (**3**) and the **method** (**7**) used.

Answer 32

1. Apparatus: - bathroom scales - a metre rule - a stopwatch 2. 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

Question 33

P6 Refraction through a glass block, using angles to plot a graph of incidence against refraction Give **apparatus** (**6**) and the **method** (**8**) used.

Answer 33

1. Apparatus: - rectangular glass block - ray box - protractor - A4 page - pencil - ruler 2. 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

Question 34

P7 Ohm’s law | (On A)

Question 35

P8 Investigate the relationship between resistance and length Give **variables** (**3**)

Answer 35

Variables: - Indy: length of wire - dep: resistance - control: temp and cross sectional area of wire

Question 36

P9 Investigating how magnetic field strength depends on: - current in a coil, - number of turns in a coil, - material of the core

Answer 36

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