Potential energy and kinetic energy confusion

Click For Summary
SUMMARY

The discussion centers on the relationship between potential energy (P.E.) and kinetic energy (K.E.) in the context of a rollercoaster scenario. The total energy of the system is 4000 joules, with a trolley mass of 20 kg and gravitational acceleration of 10 m/s². The confusion arises from the calculation method, where the teacher subtracts potential energy from total energy to find kinetic energy. This approach is correct, as the conservation of energy principle dictates that a loss in potential energy results in a gain in kinetic energy, confirming that total energy remains constant.

PREREQUISITES
  • Understanding of basic physics concepts, specifically energy conservation.
  • Familiarity with potential energy calculations, including the formula P.E. = mgh.
  • Knowledge of kinetic energy calculations, specifically K.E. = 0.5mv².
  • Basic algebra skills for manipulating equations and solving for variables.
NEXT STEPS
  • Study the principles of energy conservation in mechanical systems.
  • Learn how to calculate potential energy using the formula P.E. = mgh.
  • Explore kinetic energy calculations and practice solving for velocity using K.E. = 0.5mv².
  • Review real-world applications of energy transformations in rollercoasters and similar systems.
USEFUL FOR

This discussion is beneficial for high school physics students, educators teaching energy concepts, and anyone seeking to clarify the relationship between potential and kinetic energy in mechanical systems.

roxas
Messages
21
Reaction score
0
okay this question is confusing like everything i currently know about p.e and k.e.
okay so the maximum energy of a rollercoaster is 4000j. the mass of the trolly is 20kg, and the acceleration due to gravity is 10m/s^2(dunnoe where's the squared button on the keyboard) okay so i am supposed to calculate the velocity at this point. my teacher gave the working for this answer and he minus the potential energy from the total energy to find the k.e, and this is where i got confused. isn't the potential energy lossed =the gain of K.E? why did he minus the P.E from the T.E? help! my physics practical is a day away and i can't afford to be confuzzled.:cry: :cry:

by the way i didnt clarify this wif my teacher as i was daydreaming in class and just copied down the answer. thx:biggrin:
 
Physics news on Phys.org
The total energy consists of kinetic and potential energy, as you know already. Since total energy is conserved, maximizing kinetic energy must minimize potential energy, and vice versa. So, an object has its maximal kinetic energy when its potential energy is minimal. The same holds for maximal potential energy.
 

Similar threads

A rocket on a spring, related to potential/kinetic energy
  • · Replies 3 ·
Replies
3
Views
2K
Conservation of Momentum Problem - Mechanical and Kinetic Energies
  • · Replies 2 ·
Replies
2
Views
1K
Expression for magnitude of the constant friction force
  • · Replies 7 ·
Replies
7
Views
1K
Potential energy in solids,liquids and gases
  • · Replies 4 ·
Replies
4
Views
3K
Net work and kinetic energy (pushing a wagon to accelerate it)
  • · Replies 1 ·
Replies
1
Views
1K
Conservation of Energy with Gravitational Potential Energy
  • · Replies 6 ·
Replies
6
Views
2K
Calculating Kinetic & Potential Energy: Is it Correct?
  • · Replies 12 ·
Replies
12
Views
1K
Gravitational Potential Energy and Work Energy Theorem
  • · Replies 3 ·
Replies
3
Views
10K
Kinetic/Potential Energy in Waves
  • · Replies 3 ·
Replies
3
Views
1K
Integral for work done leading to potential energy sign confusion
  • · Replies 5 ·
Replies
5
Views
2K