Though it is not always the case, the force often opposes the motion of an object. it is exerted by a surface as an object moves across it or makes an effort to move across it.

a. gravitational
b. applied
c. fricttonal
d. normal

The freezing and boiling point of a substance changes as the air pressure around it changes. for example, at a lower air pressure (higher altitude) it is easier for water molecules to escape from liquid into the air. in a high altitude city such as denver, colorado compared to a sea-level city such as houston, texas, water

What is the freezing point of radiator fluid that is 50% antifreeze by mass? kf for water is 1.86 ∘c/m.

Describe cytokinesis in plants and animals. in animals: in plants.