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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? km/h.

Physics

1 answer:

never [62]2 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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A 15 kg bucket of water is suspended by a very light ropewrapped around a solid uniform cylinder 0.300 m in diamter withmass 12.

matrenka [14]

Answer:

Part a)

$T = 42 N$

Part b)

$v_f = 11.8 m/s$

Part c)

$t = 1.7 s$

Part d)

$F = 159.7 N$

Explanation:

Part a)

While bucket is falling downwards we have force equation of the bucket given as

$mg - T = ma$

for uniform cylinder we will have

$TR = I\alpha$

so we have

$T = \frac{1}{2}MR^2(\frac{a}{R^2})$

$T = \frac{1}{2}Ma$

now we have

$mg = (\frac{M}{2} + m)a$

$a = \frac{mg}{(\frac{M}{2} + m)}$

$a = \frac{15 \times 9.81}{(6 + 15)}$

$a = 7 m/s^2$

now we have

$T = \frac{12 \times 7}{2}$

$T = 42 N$

Part b)

speed of the bucket can be found using kinematics

so we have

$v_f^2 - v_i^2 = 2 a d$

$v_f^2 - 0 = 2(7)(10)$

$v_f = 11.8 m/s$

Part c)

now in order to find the time of fall we can use another equation

$v_f - v_i = at$

$11.8 - 0 = 7 t$

$t = 1.7 s$

Part d)

as we know that cylinder is at rest and not moving downwards

so here we can use force balance

$F = T + Mg$

$F = 42 + (12 \times 9.81)$

$F = 159.7 N$

5 0

2 years ago

Which term refers to energy derived from heat inside the earth

tino4ka555 [31]

I think the answer is Geothermal energy.

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2 years ago

A coat rack weighs 65.0 lbs when it is filled with winter coats and 40.0 lbs when it is empty. The base of the coat rack has an

Whitepunk [10]

Answer:

0.056 psi more pressure is exerted by filled coat rack than an empty coat rack.

Explanation:

First we find the pressure exerted by the rack without coat. So, for that purpose, we use formula:

P₁ = F/A

where,

P₁ = Pressure exerted by empty rack = ?

F = Force exerted by empty rack = Weight of Empty Rack = 40 lb

A = Base Area = 452.4 in²

Therefore,

P₁ = 40 lb/452.4 in²

P₁ = 0.088 psi

Now, we calculate the pressure exerted by the rack along with the coat.

P₂ = F/A

where,

P₂ = Pressure exerted by rack filled with coats= ?

F = Force exerted by filled rack = Weight of Filled Rack = 65 lb

A = Base Area = 452.4 in²

Therefore,

P₂ = 65 lb/452.4 in²

P₂ = 0.144 psi

Now, the difference between both pressures is:

ΔP = P₂ - P₁

ΔP = 0.144 psi - 0.088 psi

8 0

3 years ago

Where did the missouri compromise imaginary line run

lara31 [8.8K]

In the Missouri Compromise, the slavery line for future US states ran along the southern border of Missouri at 36 degrees north 30 minutes

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2 years ago

If an electron is accelerated from rest through a potential difference of 1200V find its approximate velocity at the end of this

kolbaska11 [484]

Answer: 2.1 × 10^7 m/s

Explanation:

Please see the attachments below

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3 years ago