Mechanical Energy and Conservation: Formulas, Examples, and Calculations in Physics

What is mechanical energy?

The sum of Potential Energy (PE) and Kinetic Energy (KE).

What does the conservation of mechanical energy state?

Mechanical energy remains constant in the absence of air resistance or friction.

Is the conservation of mechanical energy path dependent?

No, it is path independent.

What is the formula for mechanical energy?

ME = PE + KE

If PE = 100 J and KE = 0 J, what is ME?

ME = 100 J

If PE = 30 J and KE = 70 J, what is ME?

ME = 100 J

What happens to potential and kinetic energy in a pendulum?

Energy converts between potential and kinetic as it swings.

What is the equation used for problem solving in conservation of mechanical energy?

ME1 = ME2 or PE1 + KE1 = PE2 + KE2

What does PE1 = KE2 imply in a mechanical energy problem?

The initial potential energy is converted to final kinetic energy.

At Point 1, if a skater has no height, what is the GPE?

GPE = 0 J

At Point 1, if a skater is moving at 8 m/s and has a mass of 60 kg, what is the KE?

KE = 1,920 J

If a rock is held 8.5 m above the ground, what will be its velocity just before hitting the ground?

It will not be zero; calculate using conservation of energy.

What is the relationship between potential energy and kinetic energy in a closed system?

They convert into each other while keeping total mechanical energy constant.

What is the formula for gravitational potential energy (GPE)?

GPE = mgh

What does 'm' represent in the GPE formula?

Mass of the object.

What does 'g' represent in the GPE formula?

Acceleration due to gravity (approximately 9.8 m/s²).

What does 'h' represent in the GPE formula?

Height above the reference point.

What is energy?

Energy is the ability to do work.

How is energy measured?

Energy is measured in units called Joules.

What is the relationship between Joules and BTUs?

1000 Joules = 1 BTU.

What does the law of conservation of energy state?

Energy cannot be created or destroyed; it can only be transferred.

What are the five main forms of energy?

Mechanical, Heat, Chemical, Electromagnetic, Nuclear.

How is heat energy generated?

Heat energy is caused by the internal motion of atoms.

What is the difference between heat and temperature?

Heat measures energy given off, while temperature measures how much heat energy is present.

What is chemical energy?

Chemical energy comes from the breaking and reforming of bonds in chemicals.

What is electromagnetic energy?

Electromagnetic energy is associated with moving charges, such as electricity and light.

What is nuclear energy?

Nuclear energy is associated with the nucleus of an atom, released during fusion or fission.

What is potential energy?

Potential energy is stored energy that has the ability to do work.

What is gravitational potential energy (G.P.E.)?

G.P.E. is potential energy due to an object's position, calculated as G.P.E. = mass x gravity x height.

What is elastic potential energy?

Elastic potential energy is potential energy due to the compression or expansion of an elastic object.

What is kinetic energy?

Kinetic energy is energy an object has due to its motion, calculated as K.E. = 1/2mv².

What is the Work-Energy Theorem?

Work is equal to the change in kinetic energy (W = ΔKE).

How do you calculate gravitational potential energy?

GPE = mass x gravity x height (GPE = mgh).

How do you calculate kinetic energy?

K.E. = 1/2mv².

What is the formula for work done on an object?

W = ½mvf² - ½mvi².

What is the kinetic energy of a 5-g bullet traveling at 200 m/s?

K = 100 J.

What is the kinetic energy of a 1000-kg car traveling at 14.1 m/s?

K = 99,405 J.