When we walk on the ground, the friction acts as opposed to movement, as shown in the figure below. Do you give examples of how friction is responsible for wasting energy? Give suggestions to reduce energy waste due to friction. e) Why do you need to change the tires when the thread is worn? Answer: If we do not change the tire, the frictional force decreases and the vehicle can turn. Play carrom board without powder, then play with fine powder sprinkled on board. Question 11. Explain why sliding friction is less than static friction. Answer: When an object begins to slide, the contact points on its surface do not have enough time to engage in the ground contact points. Sliding friction is therefore slightly lower than static friction. 2.

The heat generated during the friction of the hands is due to the friction of the slip. Question 7. “Friction is independent of weight, but depends on the normal force between the contact surfaces where friction exists.” Do you agree with that statement? Discuss. Maria Zakharova: Yes, I agree with that statement. The above experience helps us to come to this conclusion. In both cases, we used the same brick, so the weight does not change. But when his positions have been changed, the friction changes anyway. c) Do you find similarities in the shape of an airplane and a bird? What for? Answer: Yes. The shape of the aircraft designed as a bird to reduce the friction of fluids.

Question 13. Seetha observes a moving bus with its luggage on the roof. As the bus moves slowly, the condition of the luggage on top of it changes. But as the bus accelerates and moves quickly, she noticed that the luggage on top of the bus fell into the back of the bus. This raised many doubts in his mind about the effect of the frictional force that affects both the luggage and the tires of the bus. Can you guess the questions that were raised in his head? Write them down. Answer: Examples that show that friction is friend and foe: Question 11. Identification of factors that affect fluid friction. Take a bathtub of water. Try moving your hand in the water towards the stretched fingers, i.e. ups and downs.

Now try to move your hand in the direction perpendicular to the plane of the hand, that is, back and forth. Friction limits the relative movement between two bodies in contact. This is due to uneven surfaces that prevent smooth movements. But when a lubricant is added, it fills the uneven surface and makes it smooth. This reduces the frictional force between two surfaces. Friction comes into play when two bodies come into contact with each other in relative motion. Do you agree with the statement “friction is both good and bad”? Explain with examples. Question 6. Your friend says, “The friction depends on the contact area?” How do you correct your friend through certain experiences? Answer: If it is clear that friction does not depend on the contact area, I will explain this fact to my friend by attaching a brick held horizontally to the surface to a spring balance and pulling it on the hook. I do the same experiment holding the brick perpendicular to the surface.

In the two experiments, we find no difference and I will let him conclude that the friction depends on the normal force and not on the weight of the object on the contact surface. Thus, people tend to slide on a marble floor covered with soapy water. (a) In which case is traction easy? What for? Answer: It is easy to pull if the suitcase has wheels. Try putting a book on the table. Now place the book on two to three pencils or pens without capital letters. Drag the book again. Question 16. “Reducing friction to the lowest possible level in machine tools solves the problem of the energy crisis and preserves biodiversity.” How do you support that statement? Explain. Answer: Yes, it will solve the problem of the energy crisis and preserve biodiversity, the reason for this is that most of the energy in the form of thermal energy is wasted due to friction. To develop more electric power, we rely on coal, oil, gas, nuclear and hydropower. The production of energy from these sources, with the exception of hydroelectricity, which causes severe air pollution affecting animals and plants.

It is therefore necessary to save energy by reducing friction. .