Friction(8th Grade > Physics ) Questions and Answers
Explanation:-
Answer: Option B. -> False:
B
By applyinglots of lubricants between two surfaces, we can reduce friction. However, friction can never be entirely eliminated. Some irregularities always remain on the surfaces.
Explanation:-
Answer: Option C. -> Making the surfaces more irregular:
C
Friction can be increased by making the surface irregular. By using lubricants orpowder between the surfaces, friction is reduced.Ball bearings use rolling friction instead of sliding friction. As rolling friction is less than sliding friction,friction is reduced. However, makingirregularities on the surfaceincreases roughness. As a result of this, friction is increased.
Explanation:-
Answer: Option B. -> Frictional force produces heat.:
B
Friction can produce heat. This can be observed if you rub your palms against each other. Likewise, when a meteor enters Earth's atmosphere, air applies a frictional force (air drag) against its motion. Due to this, heat is produced and the meteor starts burning.
Explanation:-
Answer: Option B. -> Sohit will have to apply a larger force.:
B
Frictional force depends on the force with which the surfaces are pressed against each other. Heavier the object, more will be the pressing force and more will be friction. This will require a larger force to overcome friction. As Sohit is pushing a heavier box on the same surface, he will have to apply a larger force.
Explanation:-
Answer: Option D. -> Upwards along the inclined plane:
D
Friction opposes relative motion between two bodies in contact.
It acts in direction so as to oppose the relative motion between the objects. As the block is sliding down the inclined plane, friction will act upwards along the plane to oppose the motion of the block.
Explanation:-
Answer: Option B. -> False:
B
As the surface of ice is very smooth, frictional force is negligibly small, which helps the skaters move around easily.
However, if the ice surface is replaced with grass, friction would increase significantly because of which skating wouldn't bepossible.
Explanation:-
Answer: Option D. -> Drag:
D
Frictional force exerted byfluids, i.e., liquids and gases on objects moving through themis known as "drag". Itis the force which opposesmotion of any object moving with respect to the surrounding fluid.
Explanation:-
Answer: Option D. -> Streamlining:
D
By polishing or using ball bearings and lubricants, we can decrease friction between two solid surfaces. However, to decrease air drag, we can use streamlined objects which can easily move through air without much resistance.
Explanation:-
Answer: Option D. -> static friction:
D
Friction that exists between two surfaces in contactwhen there is no relative motion between themis known as static friction.It is a self-adjusting force which has a maximum limit. When the applied force overcomes thismaximum value of static friction, the object starts moving. After this,kinetic or sliding friction comes into play.