Power. Uphill  You (m = 60 kg) hike up a 30° hill with a net height increase (h = 50 m). What work is done by gravity? Distance d = h / sin  = (50 m)

Slides:



Advertisements
Similar presentations
Solving Problems with Energy Conservation, continued.
Advertisements

Physics 1D03 - Lecture 22 Energy, Work and Power.
Section 8.5: Power. Power ≡ Rate at which work W is done or rate at which energy E is transformed: Instantaneous Power: P ≡ (dE/dt) = (dW/dt) For work.
Power The rate at which work is done. Objective: To define and apply the concepts of power and mechanical efficiency.
Work, Energy and Power (Chap.6 p.139) Work, Energy and Power A.Prof. Hamid NEBDI Department of Physics Faculty of Applied Science. Umm Al-Qura University.
Work and Power solutions.
Work, power and energy(2)
SPH4C Unit #3 – Energy Transformations
Chapter 7 Kinetic energy and work Key contents Work and kinetic energy Work done by gravity, springs and a variable force Power.
By-Tanmaye Gupta ENERGY IGCSE PHYSICS What is Energy? Energy is the capacity to do work. The S.I. unit of energy is Joules 1Joule = 10 7 erg
6. Work, Energy, and Power. The Dot Product 3 where  is the angle between the vectors and A and B are their magnitudes. The dot product is the scalar.
Tuesday, September 29, 2009 In olden days, something was only considered “doing work” if you were getting tired or sweaty doing it. Make up a definition.
Chapter 5 Energy Phy 2053 Conceptual Questions
Work and Energy.
"The ability of a body to perform work is, Energy". The unit of energy is, joule (J). Larger unit of energy is kilo joule (kJ). 1 kJ = 1000 J. There are.
5.5 P OWER P Power equals the amount of work done divided by the time interval during which the work is done. Power.
Power Revisited.  Power is the rate at which work is done. P = W t  Since work = a change in energy, power is the rate at which energy (changes) is.
Acceleration & Speed How fast does it go?. Definition of Motion Event that involves a change in the position or location of something.
5.5 Power It takes time to change one form of energy into another. Physicists use the word power (P) to describe the rate at which energy is transformed,
History a bit. MW/MWe/MWt MWe and MWt are units for measuring the output of a power plant. MWe  MegaWatts of electrical output MWt  megawatts.
Sect. 8-7: Gravitational Potential Energy & Escape Velocity.
Chapter 6.1 Notes Power. The time it takes to complete an activity is as important as the work required. Compare running up stairs to walking up stairs.
Work When a force acts on an object and the object moves a parallel distance.
Work and Energy.
IN TEXT CHAPTER Power and work and efficiency.
Unit 07 “Work, Power, Energy and Energy Conservation”
Power. Power  Power (P) – rate at which work is done. Also, rate at which energy is transformed.Also, rate at which energy is transformed.  P =  SI.
CHAPTER - 11 WORK AND ENERGY CLASS :- IX. 1) Work :- Work is said to be done when a force acts on an object and the object is displaced in the direction.
Chapter 9.2 Power. Power vs. Work When carrying a load up some stairs, you do the same amount of work whether you walk or run up the stairs. Whether you.
Work. Definition Work is done on an object by a constant force moving the object through a distance It is the product of the displacement and the component.
V P Power, force and velocity Power is the rate at which a force does work. The SI unit of power is the watt (W) 1 W is the rate f working of 1 J s -1.
Electrical Power & Efficiency.  I will be able to calculate cost to operate and percent efficiency of various devices.
Power Chapter 5.6 WOD is underlined. Question A 2400 kg car can slow from 10 m/s to rest in 3.2 meters.If the car has traditional friction brakes, what.
What is Energy? Physics Definition: The ability to do work Work: Force applied over a distance (W =f*d) Force: From Newton, force is the product of a mass.
Chapter 9.2 Power. Power equals the amount of work done divided by the time interval during which the work is done. 9.2 Power.
Energy Consumption Energy consumption is measured in kilowatt. hours. A kilowatt hour is the amount of energy being consumed per hour. –Energy (kwh) =
Work and Power Efficiency, Newton, Joules, Watts, Joules per second.
Horses have it… Mechanical Power. power: the rate at which… –WORK IS DONE –ENERGY IS PRODUCED OR CONSUMED –unit: WATT Definitions Equation.
Work Work done is a measure of the energy transferred. E.g. when lifting a pencil I do work against the earth’s gravity force, energy has been transferred:
Work is only done by a force on an object if the force causes the object to move in the direction of the force. Objects that are at rest may have many.
Chapter 5 Power 1. Power is the rate at which work is done. More generally, power is the rate of energy transferred by any method. 2.
Energy, Work and Power. Work, Energy and Power Objectives: Describe the relationship between work and energy Calculate the work done by a constant applied.
Chapter 13 Energy and Work Section 4 Power. Power Power is the rate at which work is done or the amount of work done in a unit of time. Power is the rate.
Unit 5: Work, Power and Energy. Work Work is done when a force causes a change in motion of an object, or work is a force that is applied to an object.
Physics Section 5.4 Define “power” Power- is the rate at which work is done or energy is transformed. P = W ∆t P = power (watts) W = work (J) t = time.
Work and Energy Objectives: Work done by Forces Power
Power. Power Power is defined as “Work per unit time”
Speed, Velocity, and Acceleration
Work and Power.
Work, Power Problems Answers
ENERGY EQUATIONS By the end of this presentation you should be able to: Calculate kinetic energy, work and power.
Power.
Energy & Its Impact on Global Society
Work & Power. Work & Power Work : one definition Energy used to move something Work = force applied x distance moved ***force and distance must be.
Work & Power. Work & Power Work : one definition Energy used to move something Work = force applied x distance moved ***force and distance must be.
Power & Efficiency.
Review for test on Energy.
Horses Have It… Power.
Power - The rate at which work is done
POWER ENERGY WORK WHEN ENERGY IS TRANSFORMED FROM ONE FORM TO ANOTHER WORK IS DONE WHEN ? WHEN ? WHEN ENERGY IS TRANSFORMED FROM ONE FORM.
how quickly work is done
Power Power is the amount of work applied over a period of time
Review for test on Energy.
Power and electrical power
The Work Energy Principle Part 6
MODULE - 1 WORK ,POWER AND ENERGY
Horses have it… Mechanical Power.
Conservation of Energy & Power
Work done = Energy Changed
Energy & Transformations
Presentation transcript:

Power

Uphill  You (m = 60 kg) hike up a 30° hill with a net height increase (h = 50 m). What work is done by gravity? Distance d = h / sin  = (50 m) / sin 30° = 100 mDistance d = h / sin  = (50 m) / sin 30° = 100 m Work done by gravity W =  mg d sin  =Work done by gravity W =  mg d sin  =  (60 kg)(9.8 m/s2)(50 m) =  30 kJ  (60 kg)(9.8 m/s2)(50 m) =  30 kJ Gravity does negative work on the hiker d = 100 m -mg

Rate of Work  You (60 kg) walk up a 30° hill with a net height increase of 50 m at 1 m/s. t = (50 m)/sin30°/(1/ms) =100 st = (50 m)/sin30°/(1/ms) =100 s W = 30 kJW = 30 kJ  You run up the same 30° hill with a net height increase of 50 m at 4 m/s. t = 25 s, W = 30 kJ But, running is harder!  The rate of work has increased by 4 times by running. Hiker does positive work to overcome gravity d = 100 m

The Watt  The rate of work is called power.  The SI unit of power is the watt (W). 1 watt = 1 J/s = 1 N m/s = 1 kg m 2 / s 31 watt = 1 J/s = 1 N m/s = 1 kg m 2 / s 3  Energy can be measured in watt-seconds = joules.

Average Power  The walker had an average power output based on the work compared to the time. P = W / tP = W / t P = 30 kJ / 100 s = 300 WP = 30 kJ / 100 s = 300 W  The runner generated the same work in one quarter of the time. P = 30 kJ / 25 s = 1200 W  When running seems harder, it isn’t work, it’s power.

Instantaneous Power  Work does not have to be uniform over time. Moving over a series of hills and valleys (changing work)Moving over a series of hills and valleys (changing work) Walking and running (changing rate)Walking and running (changing rate)  The power expended at one instant is the limit of work done over a very small time interval.

Power Plants  Electrical power is measured in watts. 60 W light bulb60 W light bulb 1000 MW power plant1000 MW power plant  The energy used is measured in power times time.  If electricity costs $ per kWh, how much does it cost to leave a a 1500 W floodlamp on all year? Energy used is W = Pt = (1500 W)(3.2 x 10 7 s) = 4.8 x J Cost is (4.8 x W s) * (1 kW / 1000 W) * (1 h / 3600 s)*(0.083 / kWh) = $1,100

Force and Velocity  Power is work per time. Work is force acting over a distanceWork is force acting over a distance Distance per time is velocityDistance per time is velocity  Power is force times velocity. next F v

Feedback: Privacy Policy Feedback
Do Not Sell My Personal Information
About project: SlidePlayer Terms of Service

© 2025 SlidePlayer.com. Inc. All rights reserved.