1- Surfactant is produced during the following period:
a. 30th Week of Gestation
b. 31st Week of Gestation
c. 32nd Week of Gestation
d. 33rd Week of Gestation
e. 34th Week of Gestation

The answer is energy. the arrows are showing how exited and energized the stones are.

It depends on the surface of the levels. the rougher the surface, the greater is the frictional force. for rougher surfaces, you would need to exert greater force to move the object. the concept is that, you must overcome the frictional force in order to bring the object into motion. this is the reason why we add lubricants to the joints so they could easily move. this answer was on