Term 1 Week 8

This week-summary week; we basically went over everything done in the past. (Also a little bit of new stuff)

(I feel like just putting the ppt here but that would be laziness)

Accuracy VS Precision

To make things clearer and easier I'll use a bulls-eye analogy

Accuracy-how close the darts are to the centre

Precision-how close the darts are to each other

Also known as: random error VS systematic error (respectively)

Length measurements:

Measuring tape and ruler-1 dp (cm)

Vernier caliper-2 dp (cm)

Micrometer screw gauge-3 dp (cm)/2 dp(mm)

Volume measurements:

Measuring cylinder-0.5 cm cube

Burette-0.05 cm cube

Pipette and volumetric flask-fixed volume

Meniscus-lowest/highest point of water level when viewed

For usual measurements e.g. measuring cylinder read concave (lower) meniscus 

For mercury thermometer read convex (higher) meniscus

Area measurement: irregular figures:

Divide area into grid.

If square is fully filled, count it.

If square is more than half filled, count it.

If square is less than half filled, do not count it.

The smaller the squares, the greater the accuracy.

Measuring time:

Stopwatch:

Digital and analogue-digital more accurate measuring 2dp; analogue can only measure 1dp

However for stopwatch 2nd dp should not be counted because of human error-unless it is not a human starting and stopping the stopwatch

Human error=0.2-0.3s

Ticker-tape timer:

Electrical device using oscillations of a steel strip to measure short time intervals

Steel strip vibrates 50 times a second and makes 50 dots a second on a paper tape being pulled past it

Distance between every two dots=distance of 0.02 seconds of motion



For pendulum:

Fudicial line-an imaginary line in the centre of each swing
Oscillation-amount of time for pendulum to pass by fudicial line twice
Period-time for one oscillation

That's all for this term! See you next time!