Energy Energy-the ability to do work. -Because work and energy are soclosely related, they are expressed in the same units. JOULES (J) When a given amount of work isdone, the same amount of energy is involved.
Kinetic Energy• Kinetic energy is energy of motion: -All moving objects have kinetic energy. - Objects with kinetic energy can do work.*When you are bowling, and you throw the ball down the lane, you are using kinetic energy.By throwing the ball, you are transferring your kinetic energy to the ball. The bowling ball will then transfer energy to the pins.
Kinetic Energy depends…..• On speed and Mass!!!• An objects kinetic energy can be determined by the following equation: » Kinetic energy= mv²/2 REMEMBER!!! V is for SPEED!!!
Previous slide continued• M=mass of object• V= objects speed• The faster something is moving, the more kinetic energy it has.• The more massive a moving object is, the more kinetic energy it has.• Speed has a greater effect on kinetic energy than mass does.
Potential Energy is Energy of Position• Potential energy- is the energy that an object has because of its position or shape.• Ex- a stretched bow, or a rubber band. When you pull back on a bow, energy is present because work was done to change its shape.
Gravitational Potential Energy• Depends on weight and height.• As you lift an object, you do work on the object by using a force that opposes gravitational force.• You then give that object gravitational potential energy. Ex- lifting up your book bag.• The amount of gravitational potential energy an object has depends on its weight and how far above Earth’s surface it is.
Gravitational Potential Energy• Gravitational Potential Energy=weight x height• Since weight is expressed in Newtons, you would work out the problem as follows:• N · M= (J)• Newtons x Meters = Joules
Mechanical EnergyMechanical Energy sums it all up.Mechanical Energy- is the total energy of motion and position of an object.Mechanical energy can be all potential energy, all kinetic energy or some of both. Mechanical Energy= potential energy + kinetic energy