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Sladkaya [172]
3 years ago
7

A cross-country skier can complete a 7. 5 km race in 45 min. What is the skier’s average speed? km/h.

Physics
1 answer:
never [62]3 years ago
8 0

The average speed is a scalar quantity. The average speed of the skier is 10 km/hrs.

<h3>What is the average speed?</h3>

It is calculated by dividing the total distance by the total time elapsed.

The

\overline{v}={\frac{\Delta x}{\Delta t}}

Where,

\overline{v} = average velocity

{\Delta x} = displacement = 7.5 km

{\Delta t} = change in time = 45  min = 0.75 hours

Put the values in the formula,

\overline{v}={\frac{7.5 }{0.75 }}\\\\\overline{v}= 10 \rm \ km/hrs

Therefore, the average speed of the skier is 10 km/hrs.

Learn more about average speed:

https://brainly.in/question/32459982

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marishachu [46]

Answer:

Explanation:

Terry can ride at a speed of

V = 30 miles in 2hours

Speed = distance / time

V = 30 /2

V = 15 mile/hour

So, we want to know the distance traveled in 1.7hours

Then,

Speed = distane / time

Distance = speed × time

Distance =15 × 1.7

Distance = 25.5 miles

So, the distance traveled in 1.7hours is 25.5 miles

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3 years ago
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A glass rod and a steel rod are of equal length at 0C. At 100C they differ in length by
NeX [460]

The given lengths at 0 °C are 2.5 m

Let l₀ be the given lengths of the glass and steel rods at 0 °C. Let l and l' be the lengths of the glass and steel rods at 100 °C respectively.

From our expression for linear expansivity,

l = l₀ + l₀αΔθ where α = linear expansivity of glass = 0.000008/°C and Δθ = temperature change = θ - θ' where θ = 100 °C and θ' = 0 °C. So, Δθ = 100 °C - 0 °C = 100 °C.

Also,

l' = l₀ + l₀α'Δθ where α' = linear expansivity of steel = 0.000012/°C and Δθ = temperature change = θ - θ' where θ = 100 °C and θ' = 0 °C. So, Δθ = 100 °C - 0 °C = 100 °C.

Since the difference in their lengths at 100 °C = 0.001 m, we have that

l - l' = l₀ + l₀αΔθ - (l₀ + l₀α'Δθ)

l - l' = l₀ + l₀αΔθ - l₀ - l₀α'Δθ)

l - l' = l₀αΔθ - l₀α'Δθ

l - l' = l₀(α- α')Δθ

Making l₀ subject of the formula, we have

l₀ = (l - l')/[(α- α')Δθ]

Substituting the values of the variables into the equation, we have

l₀ = (l - l')/[(α- α')Δθ]

l₀ = 0.001 m/[(0.000008/°C - 0.000012/°C)100 °C.]

l₀ = 0.001 m/[(-0.000004/°C)100 °C.]

l₀ = 0.001 m/-0.0004

l₀ = -2.5 m

Neglecting the negative sign,

l₀ = 2.5 m

So, the given lengths at 0 °C are 2.5 m

Learn more about linear expansion here:

brainly.com/question/14089545

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2 years ago
What is Gravity?<br>PLEASE ANSWER ​
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Answer:

Gravity is the force by which a planet or other body draws objects toward its center. The force of gravity keeps all of the planets in orbit around the sun.

<em><u>Please mark as brainliest</u></em>

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A driver in a 2290-kg car car traveling at 42.7 m/s slams on the brakes and skids to a stop. If the coefficient of friction betw
8_murik_8 [283]

Answer:

126.56 m

Explanation:

Applying,

-F = ma............. Equation 1

Where F = frictional force, m = mass of the car, a = acceleration.

Note: Frictional force is negative because it act in opposite direction to motion

But,

F = mgμ.......... Equation 2

Where g = acceleration due to gravity, μ = coefficient of friction

Substitute equation 2 in equation 1

-mgμ = ma

a = -gμ.............. Equation 3

From the question,

Given: μ = 0.735

Constant: 9.8 m/s²

Substitute these values in equation 3

a = -9.8×0.735

a = -7.203 m/s²

Finally,

Applying

v² = u²+2as.............. Equation 4

Where v = final velocity, u = initial velocity, s = distance

From the question,

Given: u = 42.7 m/s, v = 0 m/s (to a stop), a = -7.203 m/s²

Substitute these values into equation 4

0² = 42.7²+2(-7.203)s

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s = -1823.29/-14.406

s = 126.56 m

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