D. Answer the following questions in brief.
1. State the meanings of the terms (a) rolling friction
(b) fluid friction
2. State the likely cause of friction.
3. A box is resting on floor. To move it, a (variable) force is applied as shown in the diagram below. Give the answer of the questions given below.
*(a)* Give the (likely) value of the force of limiting friction.
*(b)* Why does the box stay at rest in the cases corresponding to Fig(a) and Fig(b)?
*(c)* Mark the direction of frictional force, and mention the kind of frictional force that comes into play, in each case.
4. Name the kind of frictional friction, that comes into play, when a book, kept on a collection all cylindrical pencils, is moved by pushing it.
5. Why are objects given special shapes when they are moving through fluids? write the name given to this special shapes?
Answers
Explanation:
1.a) Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the motion when a body (such as a ball, tire or wheel) rolls on a surface.
b) Fluid Friction is the force that resists motion either within the fluid itself or of another medium moving through the Fluid. There is internal friction, which is a result of the interactions b/w molecules of the Fluid, and there is external friction, which refers to how a fluid interacts with other matter.
2. Friction is a force that resist the relative motion between two object material. The causes of the resistive force are molecular adhesion, surface roughness, and deformations. Adhesion is the molecular force resulting when two materials are brought into close contact with each other.