Answer:
Total number of lamps will be 4
Explanation:
We have given power of the lamp W = 400 watt
Potential difference across the lamp V=110 volt
We know that power is equal to 
So 

Total current is given 15 A
As it is given that lamps are connected in parallel so total current is the sum of current through each lamp
So number of lamp will be 
As the lamp can not be in negative
So total number of lamps will be 4
i think photons with shorter wavelengths have larger speed.
I apologise if its incorrect.
Explanation:
a) Balloon is being thrown down and is speeding up;
mg >
b) Balloon is in the air on its way down and moving with constant speed.
=mg
c) The Balloon is on the ground and rest instantaneously
mg = Normal
d) Balloon is moving slowly downward;
e) Because, at the peak of trajectory drag force is 0.
Drag force = 0