PowerObjectives
Relate (without calculation) power to work done and time taken, using appropriate examples
Recall and use the equation P = E/t in simple systems.
Outcomes
C: Describe what power is in relation to work.
B: Calculate power for various problems.
A: Carry out multiple step calculations involving energy, work and power successfully.
Key terms: work, power, energy, time, watts, joules
PowerOutcomes
C: Describe what power is in
relation to work.
B: Calculate power for various
problems.
A: Carry out multiple step calculations
involving energy, work and power
successfully.Key terms: work, power, energy, time, watts, joules
PowerOutcomes
C: Describe what power is in
relation to work.
B: Calculate power for various
problems.
A: Carry out multiple step calculations
involving energy, work and power
successfully.Key terms: work, power, energy, time, watts, joules
PowerOutcomes
C: Describe what power is in
relation to work.
B: Calculate power for various
problems.
A: Carry out multiple step calculations
involving energy, work and power
successfully.Key terms: work, power, energy, time, watts, joules
A lawnmower engine does 10 kJ of work in 10 seconds. What is the power of the engine?
Calculating power question 1
= 1,000 W = 1 kW
power =work done
time
= 10,000 / 10
A car transfers 12 MJ of energy in 2 minutes. What is the power of the car?
Calculating power question 2
= 100,000 W = 100 kW
= 12,000,000 / 120
power =work done
time =energy transfer
time
PowerTask
Calculate the work done and power of you moving across
the classroom.
Show all measurements and calculations carried out.
Outcomes
C: Describe what power is in relation to work.
B: Calculate power for various problems.
A: Carry out multiple step calculations involving energy, work and power successfully.
Key terms: work, power, energy, time, watts, joules
PowerTask
Answer the questions on work, energy and power
Outcomes
C: Describe what power is in relation to work.
B: Calculate power for various problems.
A: Carry out multiple step calculations involving energy, work and power successfully.
Key terms: work, power, energy, time, watts, joules
Extension1. Anuar runs up a 2.91-meter high flight of stairs at a constant speed in 2.15 seconds. If Anuar’s mass is 55.9 kg, determine the work which he did and his power rating. 2. On a recent adventure trip, Lucia went rock-climbing. Lucia was able to steadily lift her 45.0-kg body 20.0 meters in 100 seconds. Determine Lucia's power rating during this portion of theclimb. 3. Hina owns a family of squirrels. The squirrels have been trained to do push-ups inrepetitive fashion. Being connected to an electrical generator, their ongoing exercise is used to help power the home. There are 23 squirrels in the family and their average mass is 1.1 kg. They do work on the "up" part of the push-up, raising their body an average distance of 5.0 cm.If the squirrels averages 71 push-ups per minute, then determine the total amount of work done in one minute and the power generated by their activity 4. An elevator motor lifts 715 kg of mass to the height of the fourth floor of an office building (11.0meters above ground level) at a constant speed in 9.35 seconds. Determine the power rating of themotor.
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