Energy And Work (1961)

[Music] [Music] has it ever happened to you one morning that you wake up feeling full of energy if you are full of energy you don't sit around the house you get out and move around and work off your energy mowing the lawn is work but this is work too the word work in science means using energy to make something move or to make something Stu MO it takes energy to do the work of moving the propeller and winding up the rubber band for it takes energy to do the work of moving the plane through the air where is that energy coming from it comes from the energy you use to do the work of winding up the rubber band but you did that 7 hours ago nevertheless that same energy is being used now to do the work of making the airplane fly it takes energy to do the work of turning the propeller and winding up the rubber band but now some of that energy is stored in the Twisted rubber band it can remain stored there as long as you like until you want to put it to use to do work [Applause] [Music] there are many ways to store energy for example it takes energy to do the work of lifting this sandbag up in the air [Music] the hanging sandbag is a supply of stored energy that energy came from the energy used to lift the sandbag we call energy that is stored potential energy potential means that it's not being used now but that it's there ready to be used to do work the potential energy can be stored as long as you like [Music] [Applause] there is potential energy in this gasoline ready and waiting to do work it's easy to move move this kind of stored energy from one place to [Music] another the potential energy stored in the gasoline will be put to work when the gasoline is burned in the engine the potential energy stored in the gasoline is being used now to do work some of the energy it takes to do this is carried by the moving ball to the other end of the alley where it does [Music] work there is energy in all moving objects the energy in moving objects is called kinetic energy the word kinetic comes from a Greek word kineticos which means to move like all energy kinetic energy the energy in moving objects can do work the energy that is in moving objects is very apparent in moving water men have long put this energy to work the kinetic and potential energy energ of the moving water does the work of turning the water wheel the energy to do the work of turning the grindstone com comes from the kinetic and potential energy of moving water today men use the energy of moving water to turn electric generators in huge power dams the energy of the moving water does the work of turning these generators which produce electric energy electric energy is like any other kind of energy it can do work making the drill spin is work it takes energy to do the work of pulling this wrecking ball back what kind of energy is in the ball now potential energy what's that it's energy stored in something ready to do work when I let go it'll do the work of moving the ball where did the potential energy come from it's part of the energy I used to do the work of pulling the ball back what kind of energy does the ball have now kinetic energy what's that it's the kind of energy that moving objects have can it do work sure energy can always do work one more question why are you so confident can you tell why for