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3 years ago

If in 30 minutes Allex runs to a store that is 4 km away, what is her average speed in km/h? km/h

Physics

2 answers:

dlinn [17]3 years ago

6 0

Im pretty sure the answer is 8km/h

grin007 [14]3 years ago

5 0

Average speed is given as the ratio of total distance traveled in a particular time interval.

t = time of travel for allex = 30 min = 30/60 hour = 0.5 hour (Since 1 hour = 60 min)

d = distance traveled in time "t" = 4 km

V = average speed of allex

Average speed is given as

V = d/t

V = 4/0.5

V = 8 km/h

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The volume of liquid flowing per second is called the volume flow rate Q and has the dimensions of [L]3/[T]. The flow rate of li

melamori03 [73]

Answer: n=4

Explanation:

We have the following expression for the volume flow rate $Q$ of a hypodermic needle:

$Q=\frac{\pi R^{n}(P_{2}-P_{1})}{8\eta L}$ (1)

Where the dimensions of each one is:

Volume flow rate $Q=\frac{L^{3}}{T}$

Radius of the needle $R=L$

Length of the needle $L=L$

Pressures at opposite ends of the needle $P_{2}$ and $P_{1}=\frac{M}{LT^{2}}$

Viscosity of the liquid $\eta=\frac{M}{LT}$

We need to find the value of $n$ whicha has no dimensions, and in order to do this, we have to rewritte (1) with its dimensions:

$\frac{L^{3}}{T}=\frac{\pi L^{n}(\frac{M}{LT^{2}})}{8(\frac{M}{LT}) L}$ (2)

We need the right side of the equation to be equal to the left side of the equation (in dimensions):

$\frac{L^{3}}{T}=\frac{\pi}{8} \frac{ L^{n}}{LT}$ (3)

$\frac{L^{3}}{T}=\frac{\pi}{8} \frac{ L^{n-1}}{T}$ (4)

As we can see $n$ must be 4 if we want the exponent to be 3:

$\frac{L^{3}}{T}=\frac{\pi}{8} \frac{ L^{4-1}}{T}$ (5)

Finally:

$\frac{L^{3}}{T}=\frac{\pi}{8} \frac{ L^{3}}{T}$ (6)

8 0

3 years ago

What is the resistance of : A) A 1.70 m long copper wire that is 0.700 mm in diameter? B) A 20.0 cm long piece of carbon with a

astra-53 [7]

Answer:

(I). The resistance of the copper wire is 0.0742 Ω.

(II). The resistance of the carbon piece is 1.75 Ω.

Explanation:

Given that,

Length of copper wire = 1.70 m

Diameter = 0.700 mm

Length of carbon piece = 20.0 cm

Cross section area $A = (2.00\times10^{-3})^2\ m$

(I). We need to calculate the area of copper wire

Using formula of area

$A=\pi r^2$

$A=3.14\times(\dfrac{0.700\times10^{-3}}{2})^2$

We need to calculate the resistance

Using formula of resistance

$R=\dfrac{\rho l}{A}$

Put the value into the formula

$R=\dfrac{1.68\times10^{-8}\times1.70}{3.14\times(\dfrac{0.700\times10^{-3}}{2})^2}$

$R=0.0742\ \Omega$

(II). We need to calculate the resistance

Using formula of resistance

$R=\dfrac{\rho l}{A}$

Put the value into the formula

$R=\dfrac{3.5\times10^{-5}\times20\times10^{-2}}{(2.00\times10^{-3})^2}$

$R=1.75\ \Omega$

Hence, (I). The resistance of the copper wire is 0.0742 Ω.

(II). The resistance of the carbon piece is 1.75 Ω.

8 0

3 years ago

Please, I need help with this question.

Jet001 [13]

The x and y components of the velocity vector is 17.32 m/s and 10 m/s respectively.

<h3>What is the x - component of the velocity?</h3>

The x-component of the ball's velocity is the velocity of the ball in the horizontal direction or x-axis.

The velocity of the ball in x-direction is calculated as follows;

Vx = V cosθ

where;

Vx is the horizontal velocity of the ball
V is the speed of the ball
θ is the angle of inclination of the speed

Vx = (20 m/s) x (cos 30)

Vx = 17.32 m/s

The velocity of the ball in y-direction is calculated as follows;

Vy = V sinθ

where;

Vy is the vertical velocity of the ball
V is the speed of the ball
θ is the angle of inclination of the speed

Vy = 20 m/s x sin(30)

Vy = 10 m/s

Learn more about x and y components of velocity here: brainly.com/question/18090230

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1 year ago

[BWS.02]If the same experiment is repeated in different parts of the world by different scientists,

guajiro [1.7K]

Answer:

the results will be the same.it may be

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3 years ago

Finn chooses to enter relationships only with people who share his interests in sports and work. Whenever he finds himself havin

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Answer:

a. collectivism

Explanation:

the practice or principle of giving a group priority over each individual in it.

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3 years ago