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aivan3 [116]
3 years ago
15

An athlete is running a 5-km race at an average speed of 8 km/h. She has to stop to tie her shoe. After tying her shoe, she cont

inues running at 8 km/h. Why would her average speed for the entire race be less than 8 km/h?
Physics
1 answer:
Ray Of Light [21]3 years ago
5 0
The total time she took to complete the race increased
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Two long, parallel wires are separated by 2.0 m. Each wire has a 28-A current, but the currents are in opposite directions. Part
BlackZzzverrR [31]

Given Information:  

Current = I = 28 A

distance between wires = r = 2.0 m

Required Information:  

Magnetic field = B = ?

Answer:  

B = 12x10⁻⁶ T

Step-by-step explanation:  

Biot-Savart Law is given by  

B = μ₀I/2πr

Where μ₀ is the permeability of free space, I is the current flowing through the wire and B is the magnitude of the magnetic field produced.  

We are asked to find the magnetic field midway between the wires so r/2 = 1

B = 4πx10⁻⁷*28/2π*1

B = 6x10⁻⁶ T

since the same amount of current flows in both wires therefore, equal amount of magnetic field will be produced in both wires

B = 2*6x10⁻⁶ T

B = 12x10⁻⁶ T

Therefore, the net magnetic field midway between the two wires is 12x10⁻⁶ T.

3 0
3 years ago
A copper wire has a radius of 3.5 mm. When forces of a certain equal magnitude but opposite directions are applied to the ends o
denpristay [2]

Answer:

The tensile stress on the wire is 550 MPa.

Explanation:

Given;

Radius of copper wire, R = 3.5 mm

extension of the copper wire, e =  5.0×10⁻³ L

L is the original length of the copper wire,

Young's modulus for copper, Y =  11×10¹⁰Pa.

Young's modulus, Y is given as the ratio of tensile stress to tensile strain, measured in the same unit as Young's modulus.

Y =\frac{Tensile \ stress}{Tensile \ strain} \\\\Tensile \ stress = Y*Tensile \ strain\\\\But, Tensile \ strain = \frac{extension}{original \ Length} = \frac{5.0*10^{-3} L}{L} = 5.0*10^{-3}\\\\Tensile \ stress = 11*10^{10} *5.0*10^{-3} \ = 550*10^6 \ Pa

Therefore, the tensile stress on the wire is 550 MPa.

8 0
3 years ago
A small child has a wagon with a mass of 10 kilograms. The child pulls on the wagon with a force of 2 newtons. What is the accel
notka56 [123]

Explanation:

F = ma

2 N = (10 kg) a

a = 0.2 m/s²

6 0
3 years ago
(30 points) Air at 500 kPa and 400 K enters an adiabatic nozzle at a velocity of 30 m/s and leaves at 300 kPa and 350 K. Using v
Sophie [7]

Answer:

Explanation:

Check attachment for solution

8 0
3 years ago
What is a reasonable estimate of the average kinetic energy of an athlete during a 100 m race that takes 10s?
arlik [135]
The average weight of an athlete should be around 60kg so from the information that the athlete can run 100m in 10s, we can calculate that their average speed is 10m/s. Using the kinetic energy formula, Ek = 1/2mv^2 we can calculate the kinetic energy using 60kg as the mass.

(1/2)(60)(10^2) = Ek

Ek= 3000J
7 0
3 years ago
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