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.
Answer:
See Explanation
Explanation:
10) From the options provided for this question, gamma particle is the most energetic. Recall that gamma rays are high energy electromagnetic radiation which are capable of causing a high degree of ionization in matter.
11) The bombardment of U-235 with neutrons leads to the reaction;
Hence
a = 92, b= 95, c= 53
12) In positron emission, a proton is transformed into a neutron. The mass number of the daughter nucleus is the same as its parent but the atomic number decreases by 1.
Hence;
The number of grams of radon 222 did it have 15.2 ago was 49.6 grams( answer C)
<u>calculation</u>
- calculate the number of half life it has covered from 15.2 days to 3.8 days
that is divide 15.2/ 3.8 = 4 half life
- half life is time taken for a radio activity of a specified isotope to fall to half its original mass
therefore 3.8 days ago it was 3.1 x2 = 6.2 grams
7.6 days ago it was 6.2 x2 = 12.4 grams
11.4 days ago it was 12.4 x2= 24.8 grams
15.2 days ago it was 24.8 x2=49.6 grams
Answer: 40.1%
Explanation: The mass of calcium in this compound is equal to 40.1 grams because there's one atom of calcium present and calcium has an atomic mass of 40.1 . The molar mass of the compound is 100.1 grams. Using the handy equation above, we get: Mass percent = 40.1 g Ca⁄100.1 g CaCO3 × 100% = 40.1% Ca.
