MECHANICAL ENERGY GRADE 10 PHYSICAL SCIENCE.

Introduction

Once again welcome to physical science grade 10. Please watch the video below for insight before getting into the task. 

https://youtu.be/Z2VrZwfoHX8

Task

A cart is on a roller coaster ride between point A,B and C.

The cart passes point A at a speed of 6 m/s. Point A IS 10 m high, B is 5 m high and C 20 m high. consider the cart as an isolated system. Ignore friction and air resistance.

  1. Define mechanical energy.                                                                                                                                                     
  2. Explain what is meant by an isolated system.
  3. How does the mechanical energy at point A compare to that at point B? explain your answer.
  4. If the cart and its passengers together have a mass of 600 kg, calculate the total mechanical energy of the cart and its passengers.
  5. Calculate the speed of the cart at point B.
  6. Determine whether the cart has enough mechanical energy to reach point C without the help on an engine.
Process
  • Define all the concepts under mechanical energy and understand what they truly mean, and how can they be applied in real life.
  • Define isolated systems and mechanical energy. 
  • Calculate mechanical energy, gravitational potential energy and kinetic energy by using relevant formulas. 
  • Gravitational potential energy is defined by the energy an object has due to its position relative to some point of reference, given by the formula Ep=mgh, with m as mass g as gravitational constant and h as the height.
  • kinetic energy can be defined as the energy an object has due to its motion , given by the formula Ek=1/2mv^2. with m as mass and v the velocity of an object squared.
  • conservation of mechanical energy : The total mechanical energy of an object in a closed system remains constant taken into consideration that air friction and resistance are ignored.
  • MECHANICAL ENERGY BEFORE IS EQUAL TO MECHANICAL ENERGY AFTER.
  • MAKE USE OF THE LINK BELOW FOR CLARITY.
  • https://youtu.be/62J1vn9NeLU
Evaluation
MARKING GUIDELINE
Defining mechanical energy and isolated system. 3 Marks each.
Correct calculation and formula for calculating mechanical energy. 4 Marks.
Correct calculation of speed an formula at point B. 4 Marks.

Correct calculations and stating whether the cart will reach point C or not.

 4 Marks.

 

Conclusion
  • By the end of this lesson each learner should be able to define mechanical energy, kinetic energy, potential energy, gravitational potential energy and conservation of mechanical energy.
  • Be able co calculate the energies using the correct formulas.
  • Calculate the mechanical energy of an object before and after in a closed system.
Credits