# Kinetic energy and Gravitational Potential Energy

• Sabeshan Ratneswaran
In summary, when calculating the wasted energy of a dropped object, you only need to consider the vertical component of its velocity. This is because gravity cannot give the object a horizontal component of velocity. However, if the object is thrown, both the vertical and horizontal components of velocity must be taken into account to calculate the total kinetic energy.
Sabeshan Ratneswaran
Hi Guys,When we are finding the wasted energy when something is dropped a tower, we do this: mgH-0.5mv^2
My question is, does the velocity of the kinetic energy have to be vertical component, or can it be the impact velocity when it hits the ground?

Thanks

If you simply drop an object,it will fall vertically. The vertical component of its motion will be its only motion. Gravity can not give it a horizontal component. If you give it a horizontal component, you have given it some KE. This then remains constant (assuming no resistance.) Only the vertical component of velocity increases as it falls. So if you are considering gravitational potential energy, you are only interested in the vertical component of motion.
For a dropped object mgH = 0.5m(vv)2
For a thrown object 0.5m(vh)2 +mgH = 0.5mv2 = 0.5m(vh)2 + 0.5m(vv)2 which reduces to the above when you cancel the horizontal component.

Sabeshan Ratneswaran

## 1. What is kinetic energy?

Kinetic energy is the energy an object possesses due to its motion. It is dependent on the mass and velocity of the object, and can be calculated using the formula KE = 1/2 * m * v^2, where m is the mass of the object and v is its velocity.

## 2. How is kinetic energy different from potential energy?

Kinetic energy is the energy of motion, while potential energy is the energy an object possesses due to its position or state. Kinetic energy is directly related to an object's motion, while potential energy is related to its position in a gravitational or electric field.

## 3. What is gravitational potential energy?

Gravitational potential energy is the energy an object possesses due to its position in a gravitational field. It is dependent on the mass of the object, the acceleration due to gravity, and the height of the object relative to some reference point. It can be calculated using the formula GPE = m * g * h, where m is the mass of the object, g is the acceleration due to gravity, and h is the height of the object.

## 4. How are kinetic energy and gravitational potential energy related?

Kinetic energy and gravitational potential energy are two forms of mechanical energy, meaning they can be converted into each other. As an object falls, its potential energy decreases and its kinetic energy increases. At the bottom of its fall, all of the potential energy is converted into kinetic energy. Similarly, when an object is thrown upwards, its kinetic energy decreases and its potential energy increases.

## 5. What is the conservation of energy principle?

The conservation of energy principle states that energy cannot be created or destroyed, only converted from one form to another. This means that the total amount of energy in a closed system remains constant. In the case of kinetic energy and gravitational potential energy, the total mechanical energy (the sum of these two forms of energy) will remain constant as long as there are no external forces acting on the system, such as friction or air resistance.

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