The answer would be D because is the strongest form of radiation
Answer: 1. Carbon dioxide is not an air pollutant
Explanation: it can be toxic and or safe
Answer:
Answers A and D are the correct solution.
Explanation:
Both pots have the same mass and the same velocity vector.
the only difference between A and D is the selection of the reference frame positive direction.
There are some missing data in the text of the problem. I've found them online:
a) coefficient of friction dry steel piston - steel cilinder: 0.3
b) coefficient of friction with oil in between the surfaces: 0.03
Solution:
a) The force F applied by the person (300 N) must be at least equal to the frictional force, given by:

where

is the coefficient of friction, while N is the normal force. So we have:

since we know that F=300 N and

, we can find N, the magnitude of the normal force:

b) The problem is identical to that of the first part; however, this time the coefficienct of friction is

due to the presence of the oil. Therefore, we have: