Question

Give reasons.
a. It is difficult to walk on wet floor.
b. Why moving parts of a machins have ball bearings?
c. Ships have streamlined shape.
d. Soles of shoes and tyres are treaded.

Answer 1

Answer:

(a)It is difficult to walk on a wet floor because layer of water makes floor smooth. The coating of water reduces the friction and the foot cannot make a proper grip on the floor and it starts getting to slip on the floor.

(b)Ball bearings, also known as anti-friction bearings, are small metallic or ceramic spheres used to reduce friction between shafts and axles in a number of applications. Ball bearings are often used in a series to absorb the weight placed on a moving part, or in individual cases to reduce friction in axle assemblies.

(c)The aeroplanes and ships have streamlined shaped bodies to reduce drag. The streamlined shaped body experiences minimum resistance when travelling through water or air. It helps to reduce friction.

(d)Insoles of the shoes, they are treated to make their surface rough so that the frictional force is increased when they are used. The tyres of the vehicle are also treaded to increase friction and prevent slipping.

Answer 2

Answer:

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Explanation:

1. a It is difficult to walk on a wet floor because layer of water makes floor smooth. 2 Ball bearings reduce vibrations and provide good stability. 3 The aeroplanes and ships have streamlined shaped bodies to reduce drag. 4Insoles of the shoes, they are treated to make their surface rough so that the frictional force is increased when they are used. The tyres of the vehicle are also treaded to increase friction and prevent slipping.