PAG 1

Question 1

What is the equipment needed for the density practical?

Answer 1

Measuring scales
Ruler
Eureka Can
Measuring cylinder
Empty Beaker

Question 2

What are the steps for determining the density of a regularly shaped solid?

Answer 2

1. Place solid on measuring scales which have been zeroed, and record the mass.
2. Using a ruler, measure and record the length, width, height of the shape.
3. Multiply the length by the width by the height to calculate the volume of the shape.
4. Divide the mass of the solid by its volume to calculate the density.

Question 3

What are the steps for determining the density of a irregularly shaped solid?

Answer 3

1. Place solid on measuring scales which have been zeroed, and record the mass.
2. Place a eureka can on a raised platform with anempty beaker beneath the spout.
3. Fill up the eureka can with water, until it begins to overflow into the beaker.
4. Carefully remove the beaker and place a measuring cylinder beneath spout.
5. Carefully submerge the solid into the eureka can, allowing water to overflow into the measuring cylinder.
6. Ensuring your eye is level with the water (accounting for parallax error) measure and record the volume of the water in the measuring cylinder.
7. Divide the mass of the solid by its volume to calculate its density.

Question 4

What are the steps for determining the density of a liquid?

Answer 4

1. Place a measuring cylinder on measuring scales, and zero the scales.
2. Pour a certain amount of liquid into the measuring cylinder and record the mass.
3. Pour a certain amount of the liquid into a measuring cylinder and record the volume.
4. Ensuring your eye is level with the liquid (accounting for parallax error) measure and record the volume of the liquid in the measuring cylinder.
5. Divide the mass of the solid by its volume to calculate the density.

Question 5

How can you correct a zero error after readings have been taken?

Answer 5

Record value of zero error when there is no object placed on the balance.
Add/subtract the value of this zero error from all readings.

Question 6

What is parallax error?

Answer 6

When you read a measuring cylinder at the wrong level (ie. not at the meniscus) you will get an incorrect value for volume. - parallax error.

Question 7

How can random errors be fixed?

Answer 7

Can be fixed with repeating and taking a mean.
Can be parallax error or reaction time (stopwatch timing).

Question 8

How can systematic errors be corrected?

Answer 8

Can be corrected by simple maths retrospectively (eg. zero error on weighing scales or vernier scales).

Question 9

How to calculate %uncertainty?

Answer 9

Absolute Uncertainty/Truth

Absolute uncertainty of ruler measurement = +-1mm