Answer:
The time required to melt the frost is 3.25 hours.
Explanation:
The time required to melt the frost dependes on the latent heat of the frost and the amount of heat it is transfered by convection to the air .
The heat transferred per unit area can be expressed as:
being hc the convective heat transfer coefficient (2 Wm^-2K^-1) and ΔT the difference of temperature (20-0=20 °C or K).
If we take 1 m^2 of ice, with 2 mm of thickness, we have this volume
The mass of the frost can be estimated as
Then, the amount of heat needed to melt this surface (1 m²) of frost is
The time needed to melt the frost can be calculated as
Answer:
The uranium in the sample of the compound is radioactive
Explanation:
Some atoms can split on their own. Some split when bombarded by energetic particles. Such atoms are said to be radioactive.
Radioactivity is borne out of the drive of an atom to reach stabillity. Every atom have a specific neutron/proton ratio which ensures stability of the nucleus. A nucleus with a stability ratio different from that which makes it stable will become unstable and split into one or more other nuclei with emissons of energetic particles.
Note: neutrons and protons dictates the mass of an atom. They are located in the nucleus which is the site for nuclear radioactive reactions.
Answer:
Negative sign says that release of heat.
Explanation:
The expression for the calculation of the heat released or absorbed of a process is shown below as:-
Where,
is the heat released or absorbed
m is the mass
C is the specific heat capacity
is the temperature change
Thus, given that:-
Mass = 25.2 g
Specific heat = 0.444 J/g°C
So,
Negative sign says that release of heat.
density is mass/volume so we do
.115/.000265
433.962 g/mL
