The Power of One Part E A sled of mass m is being pulled horizontally by a const

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The Power of One Part E A sled of mass m is being pulled horizontally by a constant diagonally upward force of magnitude F that makes an angle with the direction of motion. The Learning Goal coefficient of kinetic friction is k . The average velocity of the sled is uavg Find the average power Pavg created by force F Express your answer in terms of F, , and uav To learn the definition of power and how power, force, and velocity are related The definition of work done by a force (W-Fs) does not include time. For practical purposes, however, it is often important to know how fast work is being done. The rate at which work is being done is called power P. The average power Pavg can be calculated as Hints avg- where W is the amount of work done during the time interval avg Submit My Answers Give Up The power created by a force may be a constant; that is, work is being done at constant rate. However, this is not always the case. If the rate of performing work is changing, it makes sense to talk about the instantaneous power, defined as Let us now consider some questions that include numeric data A sled is being pulled along a horizontal surface by a horizontal force F of magnitude 600 N. Starting from rest, the sled speeds up with acceleration 0.08 m/s for minute At The Sl unit of power is the watt (W). One watt is defined as the power created when one joule of work is done each second. In equation form, one writes Part F Find the average power Pavg created by the force F Express your answer in watts to three significant figures A commonly used unit of work is the kilowatt-hour (kWh). One kilowatt-hour is the amount of work done in one hour when the power is one kilowatt. In equation form, this is Hints 1kWh = 1kVV . 1 hour = 103 w . 3.6 × 103 s = 3.6 MJ In this problem, you will answer several questions that will help familiarize you with power and enable you to derive a formula relating power, force, and velocity avg Submit My Answers Give Up Incorrect Try Again, 4 attempts remaining

Explanation / Answer

Vo = initial velocity = 0 m/s

t = time = 60 s

d = distance travelled

a = acceleration = 0.08

using the equation

d = Vo t + (0.5) a t2

d = 0 (60) + (0.5) (0.08) (60)2

d = 144 m

average work is given as

W = F d /t = 600 x 144/60 = 1440 watt

G)

Part F)

at t = 10 sec

velocity is given as

V = Vo + at

V = 0 + 0.08 x 10 = 0.8 m/s

instantenoeus power is given as
P = F . V = 600 (0.8) = 480 Watt

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