# Conservation of Energy

• soul5
In summary, the passenger car has a speed of 16.8 m/s at point A and experiences an average frictional force of 250N between point A and B. To stop the car at point B, an additional force must be applied by the brakes. The equation EK = 1/2mv^2 can be used to calculate this force by subtracting the kinetic energy at point B from the kinetic energy at point A.

## Homework Statement

A passenger car has a speed of 16.8 m/s when it reaches point A. The average frictional force between the car and the track from point A to B is 250N. At point B in addition to this frictional force, the car's breaks are applied so that the passenger car stops at point B.

Question: What additional force that must be applied by the breaks between point A and B in order to stop the car at point B?

Ek=1/2mv^2

## The Attempt at a Solution

EK is all I know.

Would I use EK at point A, subtract the Ek at point B and then solve for the force? EK = 1/2mv^2 F=m(v2-v1)/t

I would like to clarify that the law of conservation of energy states that energy cannot be created or destroyed, only transformed from one form to another. In this scenario, the initial kinetic energy of the car at point A is converted into other forms of energy, such as heat and sound, due to the frictional force acting on the car.

To calculate the additional force required to stop the car at point B, we can use the equation for work, W = Fd, where W is work, F is force, and d is distance. The work done by the brakes must be equal to the initial kinetic energy of the car, which is given by Ek = 1/2mv^2. Therefore, the additional force required can be calculated as F = (1/2mv^2)/d.

However, it is important to note that the frictional force also contributes to slowing down the car, so the total force applied by the brakes will be the sum of the additional force calculated and the frictional force of 250N. This additional force will vary depending on the distance between points A and B, but it is necessary to ensure the car comes to a complete stop at point B.

## 1. What is conservation of energy?

Conservation of energy is a fundamental law of physics which states that energy cannot be created or destroyed, but can only be converted from one form to another.

## 2. Why is conservation of energy important?

Conservation of energy is important because it helps us understand and predict the behavior of physical systems. It also allows us to find more efficient and sustainable ways to use energy.

## 3. What are some examples of conservation of energy in everyday life?

Some examples include turning on a light switch (electrical energy is converted to light energy), riding a bike (your body's chemical energy is converted to kinetic energy), and using a solar panel to power a device (solar energy is converted to electrical energy).

## 4. How is the law of conservation of energy related to the first law of thermodynamics?

The first law of thermodynamics is essentially a mathematical expression of the law of conservation of energy. It states that the total energy of an isolated system remains constant.

## 5. Can energy ever be completely conserved?

In theory, yes. According to the law of conservation of energy, energy cannot be created or destroyed. However, in practical applications, energy is often lost due to factors such as friction, air resistance, and heat transfer. Therefore, energy conservation is not always 100% efficient.