Answer:
The correct options are;
Both involve the formation of solid particles from nebular materials
Both involve the work of gravitational push on nebular materials
Explanation:
Planetesimals are thought to be the product of grains of cosmic dusts that are found in the debris and protoplanetary discs, such that hundreds of planet forming embrayos are considered to be the result of the collisions of planetesimals that collide with each other to form larger embrayos
Protoplanets is a large planetary body with a stratified interior due to internal melting that has taken place. They originate in the protoplanetary discs from the collision of planetesimals that are up to a kilometer in size.
Answer:
The final equilibrium T_{f} = 25.7[°C]
Explanation:
In order to solve this problem we must have a clear concept of heat transfer. Heat transfer is defined as the transmission of heat from one body that is at a higher temperature to another at a lower temperature.
That is to say for this case the heat is transferred from the iron to the water, the temperature of the water will increase, while the temperature of the iron will decrease. At the end of the process a thermal balance is found, i.e. the temperature of iron and water will be equal.
The temperature of thermal equilibrium will be T_f.
The heat absorbed by water will be equal to the heat rejected by Iron.

Heat transfer can be found by means of the following equation.

where:
Qiron = Iron heat transfer [kJ]
m = iron mass = 200 [g] = 0.2 [kg]
T_i = Initial temperature of the iron = 300 [°C]
T_f = final temperature [°C]

Cp_iron = 437 [J/kg*°C]
Cp_water = 4200 [J/kg*°C]
![0.2*437*(300-T_{f})=1*4200*(T_{f}-20)\\26220-87.4*T_{f}=4200*T_{f}-84000\\26220+84000=4200*T_{f}+87.4*T_{f}\\110220 = 4287.4*T_{f}\\T_{f}=25.7[C]](https://tex.z-dn.net/?f=0.2%2A437%2A%28300-T_%7Bf%7D%29%3D1%2A4200%2A%28T_%7Bf%7D-20%29%5C%5C26220-87.4%2AT_%7Bf%7D%3D4200%2AT_%7Bf%7D-84000%5C%5C26220%2B84000%3D4200%2AT_%7Bf%7D%2B87.4%2AT_%7Bf%7D%5C%5C110220%20%3D%204287.4%2AT_%7Bf%7D%5C%5CT_%7Bf%7D%3D25.7%5BC%5D)
<span>How hard the surfaces push together and the types of surfaces involved.</span>