Gravity is the correct answer.
Answer:
1963.93 Moles
Explanation:
-We know the standard conversion ratio for the volume of a mole is
Given volume of rooms as 
Convert the volume into liters:
#From our conversion ratio above, we get the volume of air molecules in moles as:

Hence, the volume of air molecules is 1963.93 Moles
To find the total number of miles traveled by a person, we add the distance that he has traveled: 3.0 + 5.00 + 4.000.
Now, to find the accurate number of significant figures when adding measurements, the basic rule for addition is to use the least number of decimal places when reporting the result.
Now, since 3.0 has the least number of decimal places, we report the sum with 1 decimal place and have 12.0 miles as the total distance traveled by the person to reach his destination.
Answer: 12.0 miles
Incomplete question. Missing part:
"it took him 10 seconds to move the couch. What was his power?"
Answer:
50 W
Explanation:
The power developed is given by:

where
W is the work done
t is the time taken
In this problem,
W = 500 J
t = 10.0 s
Substituting into the equation, we find

The final velocity of the 15 kg mass is 18.33 m/s.
<h3>
Conservation of linear momentum</h3>
The final velocity of the 15 kg mass can be determined by applying the principles of conservation of linear momentum as follows;

Where;
- m₁ is the mass of the first object = 25 kg
- u₁ is the initial velocity of the first object = 15 m/s
- m₂ is the mass of the second object = 15 kg
- u₂ is the initial velocity of the second object = -10 m/s
- v₁ is the final velocity of the first object = -2 m/s
- v₂ is the final velocity of the second object
Thus, the final velocity of the 15 kg mass after the collision is 18.33 m/s.
Learn more about conservation of linear momentum here: brainly.com/question/7538238