what is energy? energy is the ability to do work in other words, energy is transferred by a force...
TRANSCRIPT
What is Energy?
• Energy is the ability to do work In other words, energy is transferred by a force moving an object through
a distance (Work = Force x Distance) Ability to cause change Can change itself or its surroundings Measured in Joules (J)
Energy & Work
• Work is the transfer of energyExample: carrying your backpack up the stairs
You do work on the backpack by lifting it against the force of gravity…which requires energy
The energy to do the work comes from your muscles
Muscles receive energy from the food you eat
Energy in food comes from plants that have used energy of sunlight, or animals that have eaten such plants
Kinetic Energy• Energy of motion• Depends on 2 factors: Mass Speed (velocity)
𝐾𝐸=12𝑚𝑣2
What would happen to KE if we doubled the mass? KE would double
What would happen to KE if we doubled the speed? KE would quadruple
Why was KE highest at bottom?
Calculating KE
• A .10 kg bird is flying at a constant speed of 8.0 m/s. What is the bird’s KE?
Potential Energy
• Potential energy is energy that is stored as a result of position or shape
• Has the potential to do work• 2 forms of potential energy Gravitational potential energy Elastic potential energy
Gravitational Potential Energy• GPE depends on height, mass, and gravity
What happens to GPE the higher the object is? increases
𝑃𝐸= h𝑚𝑔m= mass (kg)g= gravity = 9.8 m/s2
h= height (m)
Usually relative to the ground or surface object is usually on
PE depends on where you are considering the reference line to be Has to be relative to
something
Elastic Potential EnergyPotential energy of an object that is stretched or compressed Something is said to be elastic if it springs back to its original shape after it is
stretched or compressed
Forms of energy
Forms of Energy
Mechanical
Thermal
chemical
electricalelectromagnetic
nuclear
Associated with motion and position of objects• Sum of PE and KE• Speeding trains, bouncing balls,
sprinting athletes
Motion of the particles in matter• Faster the particles are moving, more
thermal energy• Slower they’re moving, less thermal
energy
energy stored in chemical bonds
Energy stored in atomic nuclei
Form of energy that travels through space in the form of waves
Energy associated with electric charges
What are some forms of energy you notice around the room?