Answer:
D
Explanation:
Scientists use significant figures to avoid claiming more accuracy in a calculation than they actually know.
Answer:
The rate at which the container is losing water is 0.0006418 g/s.
Explanation:
- Under the assumption that the can is a closed system, the conservation law applied to the system would be:
, where
is all energy entering the system,
is the total energy leaving the system and,
is the change of energy of the system. - As the purpose is to kept the beverage can at constant temperature, the change of energy (
) would be 0. - The energy that goes into the system, is the heat transfer by radiation from the environment to the top and side surfaces of the can. This kind of transfer is described by:
where
is the emissivity of the surface,
known as the Stefan–Boltzmann constant,
is the total area of the exposed surface,
is the temperature of the surface in Kelvin,
is the environment temperature in Kelvin. - For the can the surface area would be ta sum of the top and the sides. The area of the top would be
, the area of the sides would be
. Then the total area would be 
- Then the radiation heat transferred to the can would be
. - The can would lost heat evaporating water, in this case would be
, where
is the rate of mass of water evaporated and,
is the heat of vaporization of the water (
). - Then in the conservation balance:
, it would be
. - Recall that
, then solving for
:
Answer:
a. It always points perpendicular to the contact surface.
Explanation:
"Normal" means perpendicular. Normal forces are always perpendicular to the contact surface.
Answer:
U = (ε0AV^2) / 2d
Explanation:
Where C= capacitance of the capacitor
ε0= permittivity of free space
A= cross sectional area of plates
d= distance between the plates
V= potential difference
First, the capacitance of a capacitor is obtained by:
C = ε0A/d.
Starting at the formula , U= (CV^2)/2. Formula for energy stored in a capacitor
Substitute in for C:
U = (ε0A/d) * V^2 / 2
Hence:
U = (ε0AV^2) / 2d