1. (a) Is static and kinetic friction a reaction force?
2. According to the equation Ff = u.Fnormal, the force of friction can be found by multiplying u(relationship between an object and a surface) and the perpendicular weight of the object.
Now, say you have a block lying on a flat board. When you tilt the board at an angle, the block slides down. However... there is no change in u. The block still has the same relationship with the surface of the table. If there is no change in u, then what accounts for the decreas in the force of friction(friction has to be decreasing, since the block is now sliding down).
3. A worker pulls a 200N packing crate at constant velocity across a rough floor by exerting a force F =55 N at an angle of 350 above the horizontal. What is the coefficient of kinetic friction of the floor?
A block is at rest on a rough incline as shown in the diagram (click here to see the diagram).
(b) Is normal force a reaction force? Is snow a fluid? Does newton's third law hold for fluid,like when you try to lie on water,the water exert a force on you? Does our weight act on us or on the things we are standing upon? Does normal force always equal weight? Does fluid exert a normal force on us? Is air resistance consider a normal force? Will normal force be smaller or greater than our weight? If normal force is smaller,will we sink? If normal force is greater,will we float?
(c)
i) Why do fluids allow us to move through it while solids don't?like why we can fall through air and not mountains?
ii) Is fluid resistance and upthrust the same thing?
iii) Which one is the reaction to weight?
and if one of them is,then the other is the reaction of which force,or it is the action of which force?
iv) Can we fall through mercury?
v) So do we consider some thing as fluid base on its density or what?
vi) Is there anything that does not fall through air like we do not fall through mountains?
vii) Can we swim in snow?
viii) In air,why is the air resistance dependent on the speed of the object? Why shouldn't it equal the weight at the beginning of the fall and remain constant throughout?since air resistance is a reaction force to weight,why doesn't it equal the weight at the beginnning of the fall?the body exert a force on the air,the air should exert an equal force on the body,then why in the first few seconds the weight is much greater than the air resistance?
ix) In terminal velocity in the case of free fall,is the air resistance equal in magnitude to the normal force of a body resting horizontally on the ground?
x) What is the reaction force to a body's weight in free fall?
The friction force acting on the block along the incline is
A zero B equal to the weight of the block C greater than the weight of the block D less than the weight of the block.
