A)
Advantage of Friction Disadvantage of Friction Walking on a surface Writing on a blackboard Flying of an airplane Wearing out of a shoe Wearing out of a shoe
B)
Advantage of Friction Disadvantage of Friction Flying of an airplane Writing on a blackboard Wearing out of a shoe Applying brake on a moving car Walking on a surface
C)
Advantage of Friction Disadvantage of Friction Applying brake on a moving car Flying of an airplane Writing on a blackboard Wearing out of a shoe Walking on a surface
D)
Advantage of Friction Disadvantage of Friction Applying brake on a moving car Flying of an airplane Writing on a blackboard Walking on a surface Wearing out of a shoe
Correct Answer: C
Solution :
When breaks are applied on a moving car, the break pads come in contact with the wheels and reduce the speed of the wheels due to friction between the pads and tyres. As a result, the frictional force, which acts in between the road and tyres of the car, also increases and the car stops. Without friction, it would be impossible to stop a car after starting. Therefore, this is an advantage of friction. The surface of a blackboard is made rough in order to write on it. Writing with chalk on blackboard is easy because of the friction that exists in between the tip of the chalk and the blackboard. This friction results in the deposition of chalk on the blackboard. It would not be possible to write if the blackboard is made frictionless. Therefore, this is an advantage of the force of friction. It is the friction between the foot and the road that helps us in walking. If there was no friction present there, then we would not be able to walk on the road. This is the advantage of friction. Disadvantages of friction: Sole of a shoe wears out because of heat produced by the friction. Hence, it is a disadvantage of friction. During flight, the frictional force between an airplane body and air opposes the motion of the airplane. Therefore, more energy of airplane engine is spent to overcome the resistance offered by the air friction and the speed of the airplane decreases. Therefore, this is a disadvantage of friction. The correct answer is C.
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