4:chemical properties can only be observed when a substance changes into another substance.
5: physical properties such as color and shape are easy to observe
6: in a chemical change an altered substance forms
7: cooking or baking food will result in a chemical change
8: a melting ice cube is a physical change
9: the rusting of iron is a chemical change
10: water boiling is a scientific physical change
The conservation of energy always holds true even when not clearly observable in machines that are less than 100% efficient. More often than not a machine will suffer energy losses (e.g. consider for a cooling fan: friction between the rotating blades, drag resistance in the air the fan is pushing around, resistance in the wire, and heat radiating/conducting away from the circuitry).
Answer:
Now, think on the electrons flowing through a conductor (we can think on the resistor as a simple conductor, like a piece of metal)
Inside the conductor, we have some "fixed" (they do not flow with the current) electrons, such that as the current flows in the conductor, the flowing electrons can interact with the fixed ones in the conductor. Then we can have collisions inside the conductor.
In those collisions, the flowing electrons leave energy in the conductor, and as we know, heat is a form of energy. Then when we have a lot of these collisions, the temperature of the conductor increases.
That is why electronic devices get hot.
Also, as the temperature of a conductor increases, the electrons inside of it start to move more, then the probability of an interaction with the flowing electrons increases.
Answer:
15km
Explanation:
Given parameters:
Average speed = 60km/hr
Time taken = 15min
Unknown:
Distance = ?
Solution:
The distance traveled can de derived using the expression below;
Distance = Average speed x time taken
Now let us convert the time to hr;
60min = 1hr
15min = 
= 0.25hr
Distance = 60km/hr x 0.25hr = 15km
