a) An electrician wishes to cut an iron wire (p = 9.71x10 Qm) that has 250 of resistance. The wire has a radius of 0.450mm. Approximately what length of wire has a resistanceequal to the maximum 250The length of the copper wire having a resistance of 25Q is =b) Calculate the gravitational force between the earth and the moon, if the mass of the earth is 5.98x104 kg and the mass of the moon is 7.36 x1022 kg. The mean distancebetween the earth and the moon is 3.85 x10 m and the universal gravitational constant G = 6.67 x101 Nm/kg.The gravitational force between the earth and the moon is = Learning PortalCourses -Reportse-Servicesb) A 30.0kg crate is at rest on a floor as shown. The coefficient of static friction between the crate and floor is 0.450 and the coefficient of kinetic friction is 0.350. Calculate theminimum horizontal force (F) required to make the crate start sliding.The minimum horizontal force (F) required to make the crate slide is =

Answered: Image /qna-images/answer/2586bf43-a507-4530-bc89-bb5a3c99bd06.jpg

a) An electrician wishes to cut an iron wire (p = 9.71x10 Qm) that has 252 of resistance. The wire has a radius of 0.450mm. Approximately what length of wire has a resistance equal to the maximum 250 The length of the copper wire having a resistance of 250 is = of the moon is 7.36 x1022 kg. The mean distance

a) An electrician wishes to cut an iron wire (p = 9.71x10 Qm) that has 252 of resistance. The wire has a radius of 0.450mm. Approximately what length of wire has a resistance equal to the maximum 250 The length of the copper wire having a resistance of 250 is = of the moon is 7.36 x1022 kg. The mean distance

University Physics Volume 2

18th Edition

ISBN:9781938168161

Author:OpenStax

Publisher:OpenStax

Chapter9: Current And Resistance

Section: Chapter Questions

Problem 70AP: A 10.00-meter long wire cable that is made of copper has a resistance of 0.051 ohms, (a) What is the...

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Review. When a straight wire is warmed, its resistance is given by R = R0,[1 + a(T T0)] according to Equation 27.20, where a is the temperature coefficient of resistivity. This expression needs to be modified if we include the change in dimensions of the wire due to thermal expansion. For a copper wire of radius 0.100 0 mm and length 2.000 m, find its resistance at 100.0C, including the effects of both thermal expansion and temperature variation of resistivity. Assume the coefficients are known to four significant figures.
Explain why R=R0(1 + a?T) for the temperature variation of the resistance R of an object is not as accurate as P=P0(1 + a?T) which gives the temperature variation of resistivity P.
When a straight wire is heated, its resistance changes according to the equation R = R0 [1 + (T T0)] (Eq. 17.7), where is the temperature coefficient of resistivity. (a) Show that a more precise result, which includes the length and area of a wire change when it is heated, is R=R0[1+(TT0)][1+(TT0)][1+2(TT0)] where is the coefficient of linear expansion. (See Topic 10.) (b) Compare the two results for a 2.00-m-long copper wire of radius 0.100 mm, starting at 20.0C and heated to 100.0C.
The student engineer of a campus radio station wishes to verify the effectiveness of the lightning rod on the antenna mast (Fig. P21.71). The unknown resistance Rx is between points C and E. Point E is a true ground, but it is inaccessible for direct measurement because this stratum is several meters below the Earths surface. Two identical rods are driven into the ground at A and B, introducing an unknown resistance Ry. The procedure is as follows. Measure resistance R1 between points A and B, then connect A and B with a heavy conducting wire and measure resistance R2 between points A and C. (a) Derive an equation for Rx in terms of the observable resistances, R1 and R2. (b) A satisfactory ground resistance would be Rx 2.00 . Is the grounding of the station adequate if measurements give R1 = 13.0 and R2 = 6.00 ? Explain. Figure P21.71
A child's electronic toy is supplied by three 1.58-V alkaline cells having internal resistances of 0.0200 inseries with a 1.53-V carbon-zinc dry cell having a 0.100- internal resistance. The load resistance is 10.0 . (a) Draw a circuit diagram of the toy and itsbatteries, (b) What current flows? (c) How much power is supplied to the load? (d) What is the internal resistance of the dry cell if it goes bad, resulting in only 0.500 W being supplied to the load?
When a straight wire is heated, its resistance changes according to the equation R = R0 [1 + (T T0)] (Eq. 17.7), where is the temperature coefficient of resistivity. (a) Show that a more precise result, which includes the length and area of a wire change when it is heated, is R=R0[1+(TT0)][1+(TT0)][1+2(TT0)] where is the coefficient of linear expansion. (See Topic 10.) (b) Compare the two results for a 2.00-m-long copper wire of radius 0.100 mm, starting at 20.0C and heated to 100.0C.
A 12.0-V emf automobile battery has a terminal voltage of 16.0 V when being charged by a current of 10.0 A. (a) What is the battery’s internal resistance? (b) What power is dissipated inside the battery? (c) At what rate (in °C/min ) will its temperature increase if its mass is 20.0 kg and it has a specific heat of 0.300 kcal/kg • °C, assuming no heat escapes?
A 10.00-meter long wire cable that is made of copper has a resistance of 0.051 ohms, (a) What is the weight if the wire was made of copper? (b) What is the weight of a 10.00-meter-long wire of the same gauge made of aluminum? (c)What is the resistance of the aluminum wire? The density of copper is 8960 kg/m3 and the density of aluminum is 2760 kg/m3.
Lightbulb A is marked 25.0 W 120. V, and lightbulb B is marked 100. W 120. V. These labels mean that each lightbulb has its respective power delivered to it when it is connected to a constant 120.-V source. (a) Find the resistance of each lightbulb. (b) During what time interval does 1.00 C pass into lightbulb A? (c) Is this charge different upon its exit versus its entry into the lightbulb? Explain. (d) In what time interval does 1.00 J pass into lightbulb A? (e) By what mechanisms does this energy enter and exit the lightbulb? Explain. (f) Find the cost of running lightbulb A continuously for 30.0 days, assuming the electric company sells its product at 0.110 per kWh.
Review. Ail aluminum rod has a resistance of 1.23 at 20.0C. Calculate the resistance of the rod at 120C by accounting for the changes in both the resistivity and the dimensions of the rod. The coefficient of linear expansion for aluminum is 2.40 10-6 (C)-1
An electrician wishes to cut a copper wire (ρ=1.72×10-8 Ωm) that has 10Ω of resistance. The wire has a radius of 0.625mm. Approximately what length of wire has a resistance equal to the maximum 10Ω ? The length of the copper wire having a resistance of 10Ω is = ? m b) Calculate the gravitational force between the earth and the moon, if the mass of the earth is 5.98×1024 kg and the mass of the moon is 7.36 ×1022 kg. The mean distance between the earth and the moon is 3.85 ×108 m and the universal gravitational constant G = 6.67 ×10-11 Nm2/kg2. The gravitational force between the earth and the moon is= ? N
A lightning flash during a thunderstorm can consist of one to tens of individual strokes, each with a duration between 10 and 100 milliseconds. Peak currents in a stroke can be as high as 20 kiloamperes. If a specific lightning flash has 10 separate strokes each lasting 50 milliseconds and carrying an average current of 8 kiloamperes, about how much charge gets transferred from the earth to the sky or vice versa? (Hint: the answer provided is 4000 C)