It is easier to move an object by rolling than sliding.
a)Relating with friction, give the reason for it.
b)Write down an instance where this principle is made use of.
Answers
Explanation:
a) ......
Friction is a force that resists the relative motion between two objects or materials. The causes of this 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.
b) ...........
If the density of an object is more than the density of the liquid, then it sinks in the liquid.
If the density of an object is more than the density of the liquid, then it sinks in the liquid. Archimedes' principle reasons this statement. This is because the buoyant force acting on the object is less than the weight of the object. If the density of the object is less than or equal to the density of the liquid, then it floats on the surface of the liquid. This is because the buoyant force acting on the object is equal to the weight of the object.
The statement is true.
Explanation:
a) Rolling friction helps in movement.
- Rolling friction is less than sliding friction.
- Rolling friction is the resistance offered by surface when any object is rolling on it.
- Sliding friction is the resistance offered where there is mutual sliding in bodies that are in contact with each other.
- Since the contact is minimum, so the rolling friction is also minimum.
- Force of friction depends on area of contact.
b) Examples where sliding friction and rolling friction can be used:
- Blocks kept onto each other, there is maximum contact and sliding friction helps in not letting them fall. It helps in resisting any mutual motion between the two blocks.
- While moving heavy loads, trolley with wheels are used so that minimum friction is applied and the movement becomes easier.