The vertical movement of the projectile is described by:
y = H - gt² / 2
When the cannonball is on the ground, y= 0 so:
0 = H - gt² /2
Solving for t:

The horizontally movement of the projectile is described by:
x = v₀t
Solving for v₀:
v₀ = x/t
v₀ = 175 m / 2.8 s
v₀ = 61.5 m/s
When an electric current is flowing through a wire, there is a magnetic <em>field</em> produced. The lines of magnetic force are circles around the wire.
Answer:
it is 59 degrees Fahrenheit
1) 
The capacitance of a parallel-plate capacitor is given by:

where
is the vacuum permittivity
A is the area of each plate
d is the distance between the plates
Here, the radius of each plate is

so the area is

While the separation between the plates is

So the capacitance is

And now we can find the energy stored,which is given by:

2) 0.71 J/m^3
The magnitude of the electric field is given by

and the energy density of the electric field is given by

and using
, we find
