Answer;
-Physical model
A physical representation of a real object, such as a globe of the world, is a physical model.
Explanation;
-A physical model is a simplified material representation, usually on a reduced scale, of an object or phenomenon that needs to investigated.
-The model can be used to simulate the physical conditions involved (temperature, waves, speed etc.) and to predict the particular constraints of the situation.
Answer:

Explanation:
(2.2500x10^3) x (3.00 x10^5)
First add the power values since all are to power 10 hence this will be 3+5=8
Then multiply the digit intergers ie 2.25*3=6.75
Therefore, in scientific notation this will be represented as 
The answer is 2.49 x 10^5 KJ. This was obtained (1) use the formula for specific heat to achieve Q or heat then (2) get the energy to melt the copper lastly (3) Subtract both work and the total energy required to completely melt the copper bar is achieved.
Oil is a lubricant which helps increase friction. when u spread sand on a place where oil is spilled the sand reduces friction between road and vehicle tire. the vehicle wont skid.