Answer: A if thats not right its C
Explanation:
J.J. Thompson is the scientist who recieved credit for discovering them.
Answer with Explanation:
We are given that
A.Mass,m=12 kg


Speed,v=1.5m/s
Net force in x direction must be zero



Net force in y direction








Power,P=Fv

Where 
B.Substitute the values


Answer:
We have to show surface area
,with few conditions that is by considering Force
and Pressure
to be respectively.
Explanation:
The atmospheric pressure is
on Earth's surface.
The magnitude of the force exerted on a person by the atmosphere is
.
Now to calculate surface area we can find it from
and re-arranging it to.

So plugging the values,
Surface area 
Hence from the above calculations we can say that surface area is
.
So the surface area of an average person can be said to have
, using the concept of pressure and force.