# Evan's Space

## Physical Quantities Videos

The smallest to the biggest thing in the universe.
This video shows the various prefixes used to denote very small or big numbers.

Is Usain Bolt faster than a typical car on the road with a constant speed of 60 km/h?
Calculate the average speed of Usain Bolt for the 100 m world record of 9.58 s in m/s. Then convert it to km/h to do a comparison.

Wanna watch his 200 m race?

How to use a vernier caliper?
The precision of vernier caliper is 0.01 cm (0.001 m).

How to use a micrometer screw gauge?
The precision of the micrometer is 0.01 mm

Factors that affect the period of the pendulum bob
Only length and gravitational field strength (g) affect the period.
– Length of pendulum increases, period (T) is longer
– Gravitational field strength (g) decreases, period (T) is longer (i.e. on the moon)

Mass of pendulum bob and angle of release (5 to 10 degree) will not affect the period (T).

## Setting up a retort stand and pendulum experiment

In this post, we will be going to the basics of setting up the retort stand and pendulum experiment. Most probably, this will be the first experiment which you will perform in the lab. Let’s start with the setting up the retort stand, boss and the clamp.

Next we will take a look at how you set the up the apparatus for the pendulum experiment.

How is the period affected by length, mass of bob, and angle of release? Click on this post to find out more.

## Factors that affect the period T of a pendulum

Period, T, is the time taken for one complete oscillation.

The period T of a pendulum is affected by the following factors.
1) the length of the pendulum:
– the longer the length, the longer the period (i.e. swing slower)

2) the gravitational field strength, g
– the greater the g, the shorter the period (i.e. swing faster)
(e.g. the g on earth is 10 N/kg while that on the moon is 1.6 N/kg, hence the period on           the moon will be longer)

NOTE: (common misconceptions)
Period, T, of the pendulum is NOT affected by
1) the angle of release (as long as the angle of release is between 10 to 15 degrees)
(if the angle of release is small, the swing will not be fast and air resistance will not be         significant)
2) the mass of the pendulum ball

Refer to the video below for the demonstration of the above concepts.

Pendulum: Displacement-time vs KE-time graphs

Click here to understand the concepts of Displacement-time vs Kinetic Energy-time graphs of a pendulum

How to set up the pendulum experiment?