EDI Work Done and Units Recap PDF

What is ‘work’? Learning Intention : Key Words : To understand and calculate work done by a force. Success Criteria: Work Can I explain what work means in science?...

What is ‘work’? Learning Intention : Key Words : To understand and calculate work done by a force. Success Criteria: Work Can I explain what work means in science? Energy Can I link work and energy? Can I calculate the work done by a force? Distance Force What is the equation for kinetic What is the equation for elastic energy? potential energy? What is the equation for What energy transfers occur as a gravitational potential energy? person throws a ball up in the air, and it falls back down? Homework: Quiz  What is ‘work’? Learning Intention : Key Words : To understand and calculate work done by a force. Success Criteria: Work Can I explain what work means in science? Energy Can I link work and energy? Can I calculate the work done by a force? Distance Force What is the equation for kinetic What is the equation for elastic energy? K.E. = 1/2 m v2. potential energy?elastic potential energy = 0.5 × spring constant × (extension)2 Homework: Quiz When a force moves an object, energy is transferred to the object. We would say that ‘work’ is done on the object. The energy transferred is equal to the ‘work done’. If the units of energy are joules (J), what are the units for work done? Work done is measured in Joules (J)  Learn off by heart work done = force x distance moved in direction of force metres W=F x s (m) Super challenge: Joules (J) Can you write this Newtons as a formula (N) triangle? Rub your hands together. How do they feel? Whenever work is done to overcome friction, energy is transferred as heat. Brake pads on a car get hot if they are applied for too long. Friction between the pads and wheel stops the motion. Energy is transferred from the kinetic energy store of the car to the thermal energy store of the brake pads and wheels. Example A cyclist uses a constant braking force of 140N to stop his bicycle in a distance of 24m. Calculate the work done by the braking force to stop the bicycle. Give the unit. (3 marks) 1. Underline key information 2. Write down equation 3. Substitute in numbers 4. Use a calculator 5. Add units Example A cyclist uses a constant braking force of 89N to stop his bicycle in a distance of 72m. Calculate the work done by the braking force to stop the bicycle. Give the unit. (3 marks) 1. Underline key information 2. Write down equation 3. Substitute in numbers 4. Use a calculator 5. Add units Example A cyclist uses a constant braking force of 89N to stop his bicycle in a distance of 72m. Calculate the work done by the braking force to stop the bicycle. Give the unit. (3 marks) 1. Underline key information 2. Write down equation 3. Substitute in numbers W= F x s 4. Use a calculator W= 89 x 72 5. Add units W= 6408J  Recap: Units What are the base units of each of these measurements? Temperature Mass Pressure Force Volume Distance  Recap: Units What are the base units of each of these measurements? Temperature Mass Pressure ℃ kg Pa Force Volume Distance N m3 m A base unit is the fundamental unit in which a quantity is usually given.  Knowledge check Open your ipads and write the correct letter How are ‘work done’ and ‘energy transferred’ linked? A: Work done is greater B: Energy transferred is greater C: They are equal D: Divide work done by energy transferred What are the units for work done? A: Force B: Newtons C: Joules D: Metres Convert 250cm into m. A: 2.5m B: 2500m C: 0.25m D: 25000m Which is the correct equation for force? (Rearrange W = F x s ) A: Force = work done x distance B: Force = work done ÷ distance C: Force = force x distance D: Force = distance ÷ work done What is the work done when a weightlifter uses a force of 20N to lift a weight of 50kg? A: 100J B: 2.5J C: 70J D: 1000J A cyclist accelerates from a set of lights. The driving force of the back tyre on the ground is 250N. How much work is done when the cyclist travels 5m? A: 1250J B: 50J C: 125J D: 500J Independent Practice Example A worker uses a constant force of 60N to push a box across the floor. They transfer 1680J of energy to the box. How far have they pushed the box? Give the unit. (3 marks) 1. Underline key information 2. Write down equation 3. Substitute in numbers 4. Use a calculator 5. Add units Example A worker uses a constant force of 645N to push a box across the floor. They transfer 20kJ of energy to the box. How far have they pushed the box? Give the unit. (3 marks) 1. Underline key information 2. Write down equation 3. Substitute in numbers 4. Use a calculator 5. Add units Task: Choose 1*, 2* or 3* and answer questions from the grid in your book. 1* I want to recap units and rearranging the equation 2* I would like to practice using the equation 3* I am confident using the equation and want to challenge myself with unit conversions. Show your working. Challenge 1: Answer the exam questions on google classroom Challenge 2: Answer the exam questions from the energy transfers lesson  Connect it _________________________________ _________________________________ _________________________________ _________________________________ How does the _________________________________ learning in this _________________________________ _________________________________ lesson link to _________________________________ what you _________________________________ learnt in the ___________ last lesson?