Another name for these two words is "constant" and you want to have a "constant", because you want something to compare your experimental group to, to see whether data had changed or not. So you have placebos or a double- blind to compare your experimental group to it and also so you know you don't have a bias or anything in the study.
<span>The egg doesn't break when it hits the sheet because the impact time is longer. Momentum means the egg is slowed rather than coming to an abrubt halt. The softer the object that the egg hits, the longer the time it takes to break. A sheet is so soft that the force is never high enough for the egg to break.</span>
Chemical change: a reaction/event where the chemicals/elements present before the change are NOT the same molecules present after the change.
For example, combustion reactions such as the burning of wood or rubbing alcohol are examples of chemical change. The reactants before the combustion of rubbing alcohol are CH3O (rubbing alcohol) and O2 oxygen (oxygen). The molecules present after the combustion reaction are CO2 (carbon dioxide) and H2O (water vapor).
Physical Change: a change in structure or state of a substance but, after the change the material is the same material that we started with. One example would be breaking a glass bottle by dropping it. The glass is now in smaller pieces than when we started, but the glass molecules are still glass molecules.
Hope this helped! Leave any questions you still have for me in the comments below!
Explanation:
Below is an attachment containing the solution.
369 kg
Explanation:
Step 1:
We know that the expression for potential energy is
PE = mgh
where, m =Mass
g = Acceleration due to gravity
h Height
Step 2:
Here m = ?
PE = 108486
h = 30 m
g = 9.8 ms⁻²
108486 = 
