Energy, Work and Power

Aim: How do objects store and release energy?Energy, Work and PowerWorkWhen a force moves an object, it is doing work.Work is measured in the joule (j)W = FdWork only occurs when the force and movement are in the same direction

Work ExampleHow much work is done while using a 50 N Force to hold a robot in place?

How much work is done by a robot pushing another robot back 5 m using a force of 100 N?EnergyEnergy is the measure of a systems ability to do work.Energy comes in many formsEnergy can not be created or destroyed, only converted from one type to anotherThere are many formulas for energy, depending on the type of energy we are concerned withKinetic EnergyKinetic energy is the energy that a moving object has.The faster an object, the more kinetic energy it has.The more massive an object, the more kinetic energy it has.KE = mass * velocity2 or mv2

A 30kg robot is moving at 10 m/s. What is its kinetic energy? Open Note QuizYou want to send a robot to Mars that will dig underground tunnels for future astronauts to live in.

Estimate the mass of the robot.The robot needs an acceleration of 30 m/s/s. How much thrust force will be required?Under that thrust, it moves 40,000 m before reaching escape velocity. How much work was done by the rockets?The robot is now going 12000 m/s. What is its kinetic energy?

Potential EnergyPotential energy is energy of an object due to its position or arrangement of the particles of a system.Gravitational potential energy is mass*height*gg ~ 10 m/s/sThere is also elastic, chemical and nuclear potential energy.Potential energy can be converted into heat or kinetic energy.Conservation of EnergyEnergy in a closed system is conserved.Kinetic energy becomes potential energy and potential becomes kinetic. The total energy of a closed system is constantWhat is a closed system?Are robots a closed system?A little mathIf energy is conserved, an object dropped from a height will change all its potential energy into kinetic.It has mgh potential energy at the start somgh = mv2 After doing algebra, you can see the velocity at the bottom will equal the square root of 2ghPowerPower is the rate at which work is doneThe faster you want to do work, the more power is requiredThe formula is: power = work/time orP = W/t