Mechanical Energy. Energy is the ability to do work The unit for energy is the Joule(J). Work is related to energy. The energy of motion is called kinetic energy. KE = ½ mv 2. A 20 kg object is moving at 5 m/s. What is its kinetic energy?. 250 J. Stored energy is called potential energy. - PowerPoint PPT Presentation
Citation preview
Mechanical Energy
Energy is the ability to do workThe unit for energy is the
Joule(J). Work is related to energy.
Mechanical EnergyThe energy of motion is called kinetic
energy.
KE = mv2 A 20 kg object is moving at 5 m/s. What is its kinetic
energy? 250 JStored energy is called potential energy.We will deal
with gravitational potential energy. That is energy an object has
because of its position.
PE = mghmg is the weight and h is the height off the groundA 25
kg mass is held 10 m above the ground. What is its potential
energy?2450 JGive an example of work.Where did the energy come from
to do that work?What is energy?
Law of Conservation of Energy
Energy may not be created or destroyed.
Energy may be transformed from one form to another.
A 20 kg snowboarder at rest is at a height of 15 m. What is
their potential energy? 2,940 JWhat is their kinetic energy? 0
JWhat is their total energy? 2,940 J
Assume you are still dealing with the same snowboarder. And that
they are now 10 m above the ground.a) What is their potential
energy? b) What is their total energy? c) What is their kinetic
energy? d) What is their speed? a) 1960 Jb) 2940 Jc) 980 Jd) 9.90
m/s
When the same snowboarder has reached the ground,a)what is their
potential energy? b)What is their total energy? c)What is their
kinetic energy? d)What is their speed?
