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2 years ago

A cross-country skier can complete a 7.5 km race in 45 min. What is the skier’s average speed?

Physics

2 answers:

Triss [41]2 years ago

8 0

<u>Answer</u>

2.7778 m/s

<u>Explanation</u>

Speed is rate of change of distance with time.

It is the distance covered in a unit time. SI units of speed in m/s. Other units are Km/h, knots e.t.c

Average speed = (total distance covered) / (total time taken)

= 7.5 Km / 45 Min

= 1/6 Km/Min

Or,

7.5Km = (7.5 × 1000) m = 7500 m

45 min = 45 × 60 2700 seconds

Average speed = 7500/2700

= 2.7778 m/s

Alecsey [184]2 years ago

7 0

To calculate for the average speed, we simply divide the total distance covered by the time it takes to travel that distance. In this case, we simply divide 7.5 km with 45 min. Therefore, the skier's average speed is 0.1667 km/min. Hope this helps.

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2 years ago

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Answer:

The correct answer is - oxygen.

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1 year ago

A lighthouse is located on a small island 5 km away from the nearest point p on a straight shoreline and its light makes two rev

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And also will be the radius of the circle the beam of light is generating at that point.

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r = 5.099 km

find the circumference:

C = 2*pi * 5.099 km

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2 years ago

A 0.091-in-diameter electrical wire at 90°F is covered by 0.02-in-thick plastic insulation (k = 0.075 Btu/h·ft·°F). The wire is

olya-2409 [2.1K]

Answer:

The critical radius of the plastic insulation is 0.72 inches.

Explanation:

Given that,

Diameter = 0.091 in

Thickness = 0.02 in

Initial temperature = 90°F

Final temperature = 50°F

Heat transfer coefficient = 2.5 Btu/h.ft²°F

Material conductivity = 0.075 Btu/h.ft °F

We need to calculate the critical radius of the plastic insulation

Using formula of critical radius

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Where, k = Material conductivity

h = Heat transfer coefficient

Put the value into the formula

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$r_{cr}=0.72\ inches$

Hence, The critical radius of the plastic insulation is 0.72 inches.

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2 years ago