Kinetic energy — Science definition
Defined in 4 courses:
- Energy associated with motion. (Science 6: Matter, Energy & Earth Systems)
- Energy of motion, calculated as KE = ½mv² (half times mass times speed squared). (Physical Science: Matter, Forces & Energy)
- The energy of motion; the average kinetic energy of a substance's particles is directly proportional to its Kelvin temperature. (Physical Science: Chemistry)
- The energy an object has because of its motion: KE = ½mv², measured in joules (J). (Physics & Environmental Science)
Where it is taught
- Forms of Energy & Evidence of Transfer — Energy, Heat & Thermal Design, Science 6: Matter, Energy & Earth Systems, Grade 6
- Kinetic & Potential Energy — Energy & Heat Transfer, Physical Science: Matter, Forces & Energy, Grade 8
- Kinetic Molecular Theory & Phase Changes — States of Matter & Gases, Physical Science: Chemistry, Grade 11
- Kinetic & Potential Energy — Work, Energy & Momentum, Physics & Environmental Science, Grade 12
In use
One of the most familiar forms is kinetic energy, the energy of motion: anything that's moving has it.
Kinetic & Potential Energy
Third, the particles neither attract nor repel one another, and their collisions are perfectly elastic, meaning no kinetic energy is lost when they bounce.
Kinetic Molecular Theory & Phase Changes
The energy of a moving object is its kinetic energy, KE = ½mv².
Kinetic & Potential Energy
Questions using kinetic energy
Problem 1
- An energy form can be identified without describing any process or system.
- Temperature in degrees Celsius is an amount of energy in joules.
- kinetic energy: Energy associated with motion.
- One illustrative result establishes every real condition and needs no further evidence.
Answer and explanation
kinetic energy: Energy associated with motion.
Energy associated with motion. The modeled 100 J transfers into 25 J light and 75 J thermal pathways. Mass in grams describes matter, while a temperature reading in °C is not an energy total. The unchanged casing mass does not mean no energy transfer occurred, and this illustrative partition is not a measurement of every flashlight.
Problem 2
Answer and explanation
50 J
KE = ½mv² = ½ × 4 × 5² = ½ × 4 × 25 = 50 J.
Problem 3
- doubles
- triples
- quadruples (×4)
- stays the same
Answer and explanation
quadruples (×4)
Since KE = ½mv², speed is squared, so doubling speed multiplies KE by 2² = 4.
Problem 4
Answer and explanation
18 J
KE = ½mv² = ½ × 1 × 6² = ½ × 1 × 36 = 18 J.
Taught alongside
- potential energy
- evidence
- system boundary
- uncertainty
- energy
- joule (J)
- model
- assumption
- kinetic molecular theory (KMT)
- phase change
- heating curve
- heat of fusion
- heat of vaporization
- phase diagram