plzz answer fast 1. Friction is a necessary evil. Write three points to support the statement. 2. Why is that the boats and aeroplanes are made in streamlined shapes ? 3. What causes friction? 4. Why is sliding friction less than static friction? And why is rolling friction less than sliding friction? 5. Why do we slip off and fall when we step on a banana peel? 6. Define: (a) fluid friction (b) rolling friction
Answers
Explanation:
Answer 1
- friction is said to be a necessary evil because it is useful as well as harmful .
- Friction helps us to walk , write , hold things , lift objects so it is necessary in our lives . without friction many essential processes can not be done .
- Sometimes it is evil because it causes wear and tear in many parts of machinery , loss of energy etc
Answer 2
Boats and aeroplanes are streamlined so as to reduce fluid friction.
Aeroplanes, boats, fishes and birds which move through fluids have bodies of special shape, called streamlined shape, so as to reduce the friction due to fluid and avoid energy loss.
For example,if the boat isn't streamlined, then it also has to push the water out of its way, increasing the drag force.
Answer 3
The interlocking of irregularities of the two surfaces opposes the motion of one object over the other and give rise to force of friction. Friction is caused by the interlocking of irregularities in the surface of two objects which are in contact with each other .
Answer 4
Friction comes into play when irregularities present in the surfaces of two objects in contact get interlocked with each other. In sliding, the time given for interlocking is very small. Hence, interlocking is not strong. Therefore, less force is required to overcome this interlocking. Because f this reason, sliding friction is less than static friction.
Rolling friction is the force resisting the motion when a body (such as a ball, tire, or wheel) rolls on a surface. Sliding friction is the force resisting the motion when a body slides on a surface. The force of friction depends on the area of contact between the two surfaces. As the area of contact is less in the case of rolling than in the case of sliding, rolling friction is less than the sliding friction
Answer 5
We slip when we step on a banana peel because the inner side of banana peel being smooth and slippery reduces the friction between the sole of our shoe and the surface of road
Answer 6
Fluid friction : fluid friction is friction that acts on the objects that are moving through a fluid
Rolling friction : When an object rolls over the surface of another object ,the resistance to its motion is called rolling friction
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