Starter Round the room TIME TO BEAT 2
Starter Round the room TIME TO BEAT 2. 12
Work done What is meant by the phrase “work done” and how can we work this out?
Learning Outcomes • measure the work done when a force (eg a lifting or pushing force) moves an object • look at the changes in kinetic or in potential energy when work is done by, or on, an object
What is work? ?
Work done When an object is moved by a force, work is done on the object. E. g. a car moving, a person lifting, The force transfers energy to the object. The amount of energy transferred is equal to the work done. measure the work done when a force (eg a lifting or pushing force) moves an object
Energy changes through work • What energy changes occur in the following situations. 1) 2) 3) 4) A ball rolls down the stairs. A man pushes his car along a flat road. A weightlifter lifts up his masses. An rollercoaster drops vertically 50 feet. look at the changes in kinetic or in potential energy when work is done by, or on, an object
Equation 1 Change in energy (J) = work done (J) Equation 2 Work done (J) = force (N) x distance moved (m) W=Fx. D
Example 1) A Danny pushes a wheel barrow 5 m with a force of 50 N. how much work was done? 2) Tom pushes a box 10 m with a force of 60 N. What is the work done? 3) Dougie does 100 J of work over 5 m. How much force was he exerting? 4) Tom pulls a truck 40 m using a force of 2000 N. How much work did he do?
Lets investigate. Aim : how much work is done lifting a 1 kg masses different distances. Distance lifted Force Work done. Remember 1 kg has a weight (force) of 10 N
Task • Design your own question on calculating work. Make up a scenario. Estimate the forces, work done and distances used. • Write the correct answer in the back of your book • Swap books and let someone else try your question
Task • On a sheet of a 4 paper: • Title: Equation summary sheet • On this sheet write out ALL the equations that we have used so far. Include the units. • Explain what these equations work out • GIVE AN EXAMPLE and STICK this in the front of your book
Plenary Revision card
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