Potential energy is energy an object has because of its position relative to some other object. Notice that gravitational potential energy has the same units as kinetic energy, kg m2 / s2. In fact, all energy has the same units, kg m2 / s2, and is measured using the unit Joule (J).

When an object falls, its gravitational potential energy is changed to kinetic energy. You can use this relationship to calculate the speed of the object’s descent. Gravitational potential energy for a mass m at height h near the surface of the Earth is mgh more than the potential energy would be at height 0.

Equations

The amount of Kinetic Energy that an object possesses is dependent on two factors: mass and velocity. Both of these factors are directly proportional to the kinetic energy.

Explain that there are two factors that affect how much kinetic energy a moving object will have: mass and speed.

Explanation: kinetic energy is equal to the the half of the multiple of mass and speed so the increasing and decreasing of the speed has a greatest impact on the kinetic energy.

gas

Higher objects (with further to fall) have greater potential energy. The heaviest of 2 objects at the same height has the greatest gravitational potential energy.

A free proton and free electron will tend to combine to form the lowest energy state (the ground state) of a hydrogen atom, the most stable configuration. This is because that state’s energy is 13.6 electron volts (eV) lower than when the two particles separated by an infinite distance.

Examples of Gravitational Potential Energy

• A raised weight.
• Water that is behind a dam.
• A car that is parked at the top of a hill.
• A yoyo before it is released.
• River water at the top of a waterfall.
• A book on a table before it falls.
• A child at the top of a slide.
• Ripe fruit before it falls.

For example, the lowest height in a problem is usually defined as zero potential energy, or if an object is in space, the farthest point away from the system is often defined as zero potential energy.

As an object falls under the influence of gravity, potential energy is less than kinetic energy after halfway point / before the halfway point.

Systems of objects ranging from atoms to planets can be arranged in many ways, resulting in many forms of potential energy: chemical, elastic, electrical (electromagnetic), gravitational, nuclear, and thermal energy.

A potential energy diagram shows the change in potential energy of a system as reactants are converted into products. The activation energy for a reaction is illustrated in the potential energy diagram by the height of the hill between the reactants and the products.

The potential energy measures the energy stored within the bonds and phases of the reactants and products. This potential energy is a part of the internal energy. In chemical reactions, the internal energy represents the total energy of the system and is often called enthalpy.

Endothermic processes require an input of energy to proceed and are signified by a positive change in enthalpy. Exothermic processes release energy upon completion, and are signified by a negative change in enthalpy.

Transition state

E

In summary, a collision between potential reactants will not result in a chemical reaction if either there is insufficient energy, meaning the kinetic energy of the collision is less than the activation energy, or the orientation is not correct for reaction to occur.

activation energy

U.

Types of Chemical Reactions

• Synthesis reactions. Two or more reactants combine to make 1 new product.
• Decomposition reactions. A single reactant breaks down to form 2 or more products.
• Single-replacement reactions.
• Double-replacement reactions.
• Combustion reactions.

Cooking an egg is an endothermic process because added energy makes it cooked. An egg without heats stays an (uncooked) egg. In this reaction, energy is absorbed. In an exothermic reaction, energy is released.

A catalyst increases the rate of reaction without being consumed in the reaction. In addition, the catalyst lowers the activation energy, but it does not change the energies of the original reactants or products, and so does not change equilibrium.