Mechanical Energy
Understanding the relationship between position, motion, and energy conservation
Key Concept: Mechanical Energy is the sum of potential energy (energy of position) and kinetic energy (energy of motion). In the absence of friction, total mechanical energy is conserved.
Energy Conservation Simulator
Watch how energy transforms as the car moves along the track
1. Gravitational Potential Energy (GPE)
Gravitational Potential Energy
Energy an object possesses due to its height above a reference point.
Key Concept: If height (h) doubles, GPE also doubles. Energy is directly proportional to height.
GPE Calculator
2. Kinetic Energy (KE)
Kinetic Energy
Energy an object possesses due to its motion.
Key Concept: If velocity doubles, KE quadruples (because v is squared). Speed has a huge effect on kinetic energy!
KE Calculator
3. Mechanical Energy (ME)
Mechanical Energy
The sum of potential and kinetic energy at any point.
Total Mechanical Energy Calculator
4. Conservation of Mechanical Energy
Energy Conservation Demo
Adjust the height to see how GPE converts to KE
Principle: As height decreases, GPE converts to KE. Total ME remains constant!
Law of Conservation of Mechanical Energy: In an isolated system (no friction), total mechanical energy remains constant. Energy lost in height = energy gained in speed.
Important Exam Tip
In Grade 10, most problems assume no friction or air resistance. If a question mentions friction, it means mechanical energy is NOT conserved because some energy is lost as heat. Always check the conditions!
Practice Problem
A 2 kg ball is dropped from a height of 10 m. What is its velocity just before hitting the ground? (Ignore air resistance, g = 10 m/s²)
Match the Formula
Complete the Sentences
Gravitational potential energy depends on .
Kinetic energy depends on mass and the square of .
If there is no friction, mechanical energy is .
Test Your Understanding
1. What happens to GPE when height is tripled?
2. A 1 kg object has 50 J of KE. What is its velocity?
3. What is the total mechanical energy of a 2 kg object at 5 m moving at 4 m/s? (g = 10 m/s²)
4. When is mechanical energy NOT conserved?
Key Terms
Key Takeaways
- GPE = m·g·h - energy due to height (directly proportional to height)
- KE = ½mv² - energy due to motion (proportional to v²)
- ME = GPE + KE - total mechanical energy
- If velocity doubles, KE quadruples (because v is squared)
- If height doubles, GPE doubles
- Law of Conservation of ME: In isolated systems (no friction), total ME remains constant
- Energy transforms: GPE ↔ KE (e.g., falling object, pendulum, roller coaster)
- If friction is present, ME is NOT conserved - some energy becomes heat
- Always check exam questions for mention of friction!
