<u>Answer</u>
Part 1) Increase
Part 2) expand
Part 3) rise
<u>Explanation</u>
When the air is heated the molecules gain kinetic energy and starts to collide with walls of the ballon making it to increase it size.
Thus the volume of the balloon expands. When this happens the balloon and its content becomes less dense and it rises.
Psychophysics is the scientific study
The power developed is 500 W ( to the nearest Watt)
Power(P) is the rate at which work is done. Work done (W) is the product of the force applied on the object and the displacement (s) made by the point of application of the force.


Therefore,

Substitute the given values of force , displacement and time


Thus the Power can be rounded off to the nearest value of 500 W
13.1 km/s, that is the mean orbital velocity of Jupiter around the sun
It is an example of balanced force.
hope this helps. good luck