So it's safe to use a mobile phone in a petrol station. But not wearing nylon. For more on this, read the Straits Times article : http://www.straitstimes.com/asia/se-asia/use-of-mobile-phones-at-petrol-stations-do-not-cause-fires-experts

It's interesting to note the differing views regarding the explanation for how a thin stream of water can get bent when a charged object is placed near it. It started with these two videos from Veritasium: This video then sets out to disprove Veritasium's model of ions being removed from the water stream.

This simulation allows students to observe the variation of gravitational field strength and potential between two masses. Field strength is shown as vectors whereas potential is shown as scalar values on a plot. The resultant field strength and potential are shown in red.

https://ejss.s3.ap-southeast-1.amazonaws.com/gravitation_Simulation.xhtml

The following simulation allows users to observe the effect of air resistance on a parachutist before and after he opens his parachute. Try to open the parachute when the man first reaches terminal velocity and observe the changes in velocity.

In this simulation, students can observe the variation of the normal contact force (N) and its effect on acceleration and velocity as an elevator moves upward.

Questions for students to work on can include:

1. Express the acceleration as a function of Normal Contact Force (N), Weight (W) and mass of the man.
2. Determine the distance travelled by the elevator.
3. Predict how the forces, acceleration and velocity will differ if the elevator was moving down instead.