You saw that if you apply the force along the left, friction acts along the right. If you apply the more information force along the right, the friction acts along the left direction. In both cases the force opposes the motion of the book. The force of friction always opposes the applied force. In sliding friction, the time given for interlocking is very small, hence, interlocking is not strong.
What role does friction play in the sport of your choice? Collect some pictures of that sport in action where friction is eithersupporting it or opposing it. Display these pictures with proper captions on the bulletin board of your classroom. An object changes its speed when an external force is applied to it. This force can either increase or decrease the object's speed depending on its direction and magnitude.
- It wears out the materials whether they are screws, ball bearings or soles of shoes (Fig. 12.8).
- In sliding friction, the time given for interlocking is very small, hence, interlocking is not strong.
- You might have observed that the jar of a mixer becomes hot when it is run for a few minutes.
- Thus, to push the heavier box, Seema has to apply a greater force than Iqbal.
- Friction comes into play when irregularities present in the surface of two objects in contact get interlocked with each other.
- An air cushion between the moving parts is used to reduce friction.
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Friction Class 8 Extra Questions Short Answer Questions
When the box starts sliding, the contact points on its surface, do not get enough time to lock into the contact points on the floor. The force required to overcome friction at the instant an object starts moving from rest is a measure of static friction. On the other hand, the force required to keep the object moving with the same speed is a measure of sliding friction.
The frictional force also depends on the shape of the object and the nature of the fluid. The frictional force exerted by fluids is also called drag. As you have seen in the previous section, friction is desirable in some situations.
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In some situations, however, friction is undesirable and we would want to minimise it. Imagine that friction suddenly vanishes. Give examples to show that friction is both a friend and a foe. (a) Friction opposes the _______________________between the surfaces in contact with each other. You will find the answers to such questions in this chapter. A battle line is a notional line on either side of whichopposing forces are arranged in the military.
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Friction between two flat surfaces is distinguished as being either static friction or?
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Put a mark with a pen at any point A on the inclined plane. Now let a pencil cell move down from this point. How far does it move on the table before coming to rest? Now spread a piece of cloth over the table. Make sure that there are no wrinkles in the cloth. (a) wet marble floor, dry marble floor, newspaper and towel.