Answer:The amount if mass of all substances before or after a chemical change are equal
Explanation:
Newtons First Law of Motion:
An object at rest stays at rest and an object in motion<span> stays in </span>motion <span>with the same speed and in the same direction unless acted upon by an unbalanced force.</span>
Therefore, the relationship between force and motion is that it takes force to change the speed or direction of any object in motion.
Given
Three 7 ohm resistor are in series.
The battery is V=10V
To find
The equivalent resistance
Explanation
When the resistance are in series then the resistance are added to find its equivalent.
Thus the equivalent resistance is:

Conclusion
The equivalent resistance is 21 ohm
The railroad tracks will expand because the heat waves make them bigger