<u>Answer:</u>
Yes
<u>Explanation:</u>
Average velocity is the ratio of total displacement and time taken for that displacement:

This means if displacement is zero, then average velocity will also be zero.
Displacement is zero when an object moves some distance in one direction, and then moves the same distance but in the opposite direction.
∴ As it is possible for displacement to be zero, it is also possible for average velocity to be zero.
Answer: 2934.75 Joules
Explanation:
Potential energy can be defined as energy possessed by an object or body due to its position.
Mathematically, potential energy is given by the formula;
<em>P.E = mgh</em>
Where P.E represents potential energy measured in Joules.
m represents the mass of an object.
g represents acceleration due to gravity measured in meters per second square.
h represents the height measured in meters.
Given the following data;
Weight =645
Height = 4.55
<em>P.E = mgh</em>
But we know that weight = mg = 645N
Substituting into the equation, we have;
<em>P.E = 645 • 4.55</em>
<em>P.E = 2934.75J</em>
Potential energy, P.E = 2934.75 Joules.
<span>The standard DH for this reaction is -852 kJ/rxn. When attacking a problem like this, the first thing to always do is to convert grams (which is a unit of measurement) into moles (which is a unit of chemistry). The atomic weight of aluminum is 26.98 g/mol, so you can divide your mass by the molecular weight to find that you have 1.81 mol of aluminum. Note then that you use up two moles of aluminum per reaction cycle (as defined by the coefficient), so you can divide your number of moles of aluminum by 2 mol Al/rxn. So now you know that you have enough aluminum for .903 reaction cycles, so you can multiply your standard enthalpy by the number of reaction cycles that can progress, and you should end up with a total of -769 kJ of energy, which equates to a release or evolution (rather than an absorption) of 769 kJ of energy.</span>
Answer:
60 seconds.
Explanation:
2400 divided by 40 equals 60