[Physics Class Notes] on Kinetic Energy Pdf for Exam

Kinetic energy is defined as the energy that is produced by an object due to its motion. When an object is set to acceleration, there is a definite need to apply certain forces. The application of force needs work, and after the work is done, the energy gets transferred to the object making it move at a constant velocity. 

Here, the energy transferred is referred to as kinetic energy and depends on the speed and mass of the object being set in motion.

Fun Facts: As we move ahead on this page, you will understand how energy in an object changes from one form to another. For instance, take a flying squirrel that has collided with a chipmunk in its rest state. After the collision, there will be a flow of kinetic energy resulting in the squirrel to transform its energy into some other forms. It will come to rest and then the kinetic energy will be zero.

How Can We Calculate Kinetic Energy?

In order to find out the kinetic energy, there needs to be some reasoning platform. Some of the findings are required, like the work done (W), by force (F). So, for instance, consider a box of mass m that is being pushed to a distance d because of the application of a force parallel to the surface. 

Looking at the definition of work done, it is the product of force and distance.

W​=F⋅d

    =m⋅a⋅d​

From the kinematic equations of motion, it is stated that we could substitute the acceleration a if the initial and final velocity v and v0​ and the distance d. Is given:

So, from that, we derive: 

[ v^{2} = v_{0}^{2} + 2ad ]

gives us, [a = frac{v^{2} + v_{0}^{2}}{2d}]

When a net amount of work is done, the kinetic energy K does change.

Kinetic Energy: [ K = frac{1}{2} m v^{2}]

In other words, the change in kinetic energy is equal to the net work done on a system or an object.

[ W _{net} = triangle K ]

The above-mentioned formula is said to be the work-energy theorem and applies in a general sense. When forces act in different magnitudes and directions, it is imperative to know the conservative forces and conservation of energy. Here, the conservative force is a force where the total work done in any moving object between two definite points is independent of the path taken. Whereas, the conservation of energy states that the sum total energy of any isolated system doesn’t change over the time.

Examples of Kinetic Energy and Potential Energy

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Kinetic Energy Examples

Bearing in mind the above formula for kinetic energy, look at a few of the examples seen in everyday life situations. 

1. An aeroplane has huge kinetic energy in flight because of its faster velocity and huge mass.

2. A baseball after it is thrown, it will have a large amount of kinetic energy because of its high velocity, and despite its smaller size and mass.

3. A downhill skier coming down from above will show immense kinetic energy because of its high velocity and mass.

4. Before a golf ball has been struck shows zero kinetic energy as its velocity is zero.

5. When an asteroid falls at an incredible speed, it has a huge amount of kinetic energy.

6. A car travelling down the road has less kinetic energy as compared to that of a semi-truck because of the less mass of the car than the truck.

What is Potential Energy?

The form of energy by virtue of which energy is stored in an object due to some position and relative to some other position at rest is known as potential energy. Three types of energy effects are shown here viz: nuclear energy, chemical, and potential electrical. This can be measured based on the distance, height, or mass of the object. It is measured in Joules.

Examples of Potential Energy:

1. A rocket sitting at the cliff’s edge. When the rock falls, the potential energy gets converted to kinetic energy.

2. Tree branches up high can fall into the ground, so they have potential energy.

3. A dynamite stick has chemical potential energy. After the release, it will get fused to contact with the chemical; it will be activated.

4. Foods that we intake provide us with energy due to the chemical potential energy. It helps with basic metabolic activities inside us.

5. A spring stretched in a pinball machine can move the call after it is released. This produces elastic potential energy.

6. Crane, when swings in a wrecking ball gain much energy even to crash the buildings

Kinetic Energy Units

When we take the unit of mass as kilogram and velocity as a metre per sec, the kinetic energy has the unit of kilograms metre square per Second Square. It is usually measured in Joules. So, the SI unit of kinetic energy is Joule (J), which is precisely 1kg.m².

Conclusion

Kinetic energy is the energy generated by an object as a result of its motion. There is a clear necessity to apply forces when an item is set to accelerate. Work is required for the application of force, and after the work is completed, the energy is delivered to the object.