HOOKE'S LAW Introduction In physics, Hooke's Law is one of the fundamental principles governing how objects deform under external forces . Named after the 17th-century British physicist Robert Hooke, this law provides a crucial understanding of the behavior of elastic materials, such as springs and rubber bands. Whether stretching a rubber band or compressing a spring, Hooke's Law helps explain what happens when forces act on these materials. What is Hooke's Law: Hooke's Law states that the force F needed to extend or compress a spring by some distance x is proportional to that distance. Mathematically, it is expressed as: F= -kx Here k represents the spring constant, which is the measure of the stiffness of the spring, and x is the displacement from the displacement position. The negative sign indicates that the force exerted by the spring is in the opposite direction of the displacement. Understanding the Spring Constant: The spring constant k is a critical co
Friction
Before discussing what is Friction? Lets consider a scenario, suppose you are continuously paddling a bicycle, but when you stop paddling the cycles got stopped after covering some distance. Do you know why is that so?
Naturally there must be some force that stops the moving objects. The Force not only helps the objects to move it also stops the moving objects.
On the other hand, suppose you kick a ball after covering a distance it got stopped. Why it got stopped?
In both the cases two forces acting on both the bodies parallelly.
One is Normal force (R) which is applied by you to move the object, and another is limiting force (Fs) which acts in opposite direction to stop the moving object.
As we can observe in above figure, when a car is moving there are two forces acting on it.
1. R which is Normal Force applied by engine of the car.
2. Fs which is Limiting force it is frictional force which is opposing the normal force.
Definition of Friction:
"The force that opposes the motion of moving objects is known as Friction."
- Friction is a force that comes in action as soon as a body is pushed or pulled over the surface.
- In case of solids, force of friction depends upon,
- Nature of two surfaces in contact.
- Pressing force between them
- Friction is contact force caused by the roughness of the materials in contact.
- Fractional forces are always parallel to the plane of contact between to bodies, but opposite in direction.
- Friction is self adjusting force.
Table For Different Values of Coefficient of Friction
There are wide variety of advantages of friction, but on the other hand it has certain disadvantages.
Advantages:
- Friction enables us to walk on the ground.
- Friction protects us from sliding as sand is thrown to maintain friction on inclined railways track during rain.
- The brakes of the car to help it slow down and stop safely.
- A large amount of energy is wasted in the machines due to friction.
- Friction leads to wear and tear of the parts hence increases the service cost.
- Failure of oil pump in car in car engine result contact between dry metals which yields high temperature hence the car engine is seized.
Friction can be reduced by,
- Making the sliding surfaces smooth.
- Making the fast moving objects streamline shape (Fish shape), such as cars, airplanes e.t.c. This causes smooth flow of air and thus minimizing air resistance at high speeds.
- Lubricating the sliding surfaces.
- Using ball bearing or roller bearing. Because the rolling friction is lesser than the sliding friction.
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