A positive acceleration indicates that the object sped up. This means that if you compare the first speed to the second, the second speed should be higher.
A negative acceleration indicates that the object has slowed down. This means that if you compare the first speed to the second, the second speed should be lower.
If an acceleration is 0, it means that it neither slowed down nor sped up.
Now let us analyze your problem by listing down the speed and the time:
At noon: 4 mi/hr
12:30 : 6 mi/hr
2:30 : 2 mi/hr
From noon to 12:30, you will notice that there is an increase in speed. This means that Tommy had a positive acceleration. (Rules out D.)
From 12:30 to 2:30, there is a decrease in speed. This would indicate that Tommy had a negative acceleration. (Rules out C.)
No speed was the same, so acceleration was never 0. (Rules out A.)
From the assumptions above, we can now deduce that the answer is B.
02(g) = 0 kj/mol
<span>CO2 (g) = -393.5 kj/mol </span>
<span>H20(g) = -241.8 kj/mol </span>
<span>H total = -5094 kJ
</span>5094kJ = [8(-393.5) + 9(-241.8)] - [X + 12.5(0)]
<span>-5094 kJ = [-3148 + (-2176.2)] - [x + 0] </span>
<span>-5094 kJ = -5324.2 - x </span>
<span>add -5324.2 to -5094 </span>
<span>to get +230.2 = -x </span>
<span>move the negative to the other side </span>
<span>and you get -230 kj/mol</span>
The Density of the metal is 5.6 g/cm³
<h3>What is the density of a substance?</h3>
The density of a substance is the ratio of the mass and the volume of the substance.
The density of the metal is calculated as follows:
mass of metal = 1.4 kg = 1400 g
volume of metal = 3.2 * 17.1 * 4.6 = 251.712 cm³
Density of metal = 1400 g/251.712 cm³
Density of the metal = 5.6 g/cm³
Therefore, the density of the metal is obtained from the mass and the volume of the metal.
Learn more about density at: brainly.com/question/1354972
#SPJ1
A compound that yields hydrogen ions when dissolved in a solution is an acid.
An example is an <em>aqueous solution of HCl.</em>
