A flask with a tap has a volume of 200cm3 when full of air, tye flask has a mass of 30.98g. the flask is connected to vacuum pump, the air is pimped put and then the tap is closed, the flask now has mass of 30.72g calculate:
a. the mass of air in the flask before connecting to vacuum pump, in g
b. the density of the air in the flask

when insulating materials rub against each other, they may become electrically charged . electrons , which are negatively charged, may be 'rubbed off' one material and on to the other. the material that gains electrons becomes negatively charged. the material that loses electrons is left with a positive charge.

explanation:

as the height from which the ruler was dropped increased, the speed of the ruler at ryan's hand increased.