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3 years ago

8

A tunnel has a length of 50 km. A car takes 20 min to travel between the two ends of the tunnel. What is the average speed of th

e car

1 answer:

Luda [366]3 years ago

7 0

Answer:

150 km/h

Explanation:

50km/20min = x km/60 min

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Why do temperatures on the moons surface vary ncyb more than temperatures on earth

ollegr [7]

Answer:

The moon has no atmosphere

Explanation:

The temperatures on the surface of the Moon vary much more than those on Earth because the moon has no atmosphere (third answer in the list), and therefore there are no molecules that could retain residual heat and make the change from day to night a softer transition.

5 0

3 years ago

A guitar string vibrates at a frequency of 330Hz with wavelength 1.40m. The frequency and wavelength of this sound wave in air (

bixtya [17]

Answer:

Same frequency, shorter wavelength

Explanation:

The speed of a wave is given by

$v=f\lambda$

$\lambda=\dfrac{v}{f}$

where,

f = Frequency

$\lambda$ = Wavelength

It can be seen that the wavelength is directly proportional to the velocity.

Here the frequency of the sound does not change.

But the velocity of the sound in air is slower.

Hence, the frequency remains same and the wavelength shortens.

7 0

3 years ago

What is the volume V of a sample of 4.00 mol of copper? The atomic mass of copper (Cu) is 63.5 g/mol, and the density of copper

rusak2 [61]

Answer : The volume of a sample of 4.00 mol of copper is $28.5cm^3$

Explanation :

First we have to calculate the mass of copper.

$\text{ Mass of copper}=\text{ Moles of copper}\times \text{ Molar mass of copper}$

$\text{ Mass of copper}=(4.00moles)\times (63.5g/mole)=254g$

Now we have to calculate the volume of copper.

Formula used :

$Density=\frac{Mass}{Volume}$

Now put all the given values in this formula, we get:

$8.92\times 10^3kg/m^3=\frac{254g}{Volume}$

$Volume=\frac{254g}{8.92\times 10^3kg/m^3}=2.85\times 10^{-2}L=2.85\times 10^{-2}\times 10^3cm^3=28.5cm^3$

Conversion used :

$1kg/m^3=1g/L\\\\1L=10^3cm^3$

Therefore, the volume of a sample of 4.00 mol of copper is $28.5cm^3$

7 0

3 years ago

Read 2 more answers

If the torque required to loosen the nut that is holding a flat tire in a place on a car has a magnitude of 35 N•m what minimum

VashaNatasha [74]

Answer: F = 130 N

Explanation: Solution:

Convert first 27 cm to m.

27 cm x 0.01 m / 1 cm = 0.27 m

Calculate the torque using T = Fd

Derive to find force F

F = T /d

= 35 N.m / 0.27 m

= 130 N

4 0

3 years ago

Read 2 more answers

Toby's Trucking Company determined that on an annual basis, the distance traveled per truck is normally distributed, with a mean

Reptile [31]

Answer: 56994 miles

Explanation:

Given : Toby's Trucking Company determined that on an annual basis, the distance traveled per truck is normally distributed with

$\mu=50,000\text{ miles}$

Standard deviation : $\sigma=12,000\text{ miles}$

Let a be the distance traveled by at least 72% of the trucks.

Let X be the random variable that represents the distance traveled by a truck

Then $P(x\geq a)=0.72$

The critical value corresponds to p-value 0.72 : $z=0.5828415$

Also, $z=\dfrac{x-\mu}{\sigma}$

$\Rightarrow\ 0.5828415=\dfrac{a-50000}{12000}\\\\\Rightarrow\ a=12000(0.5828415)+50000=56994.098\approx56994$

Hence, 56994 miles will be traveled by at least (equal to and more than) 72% of the trucks .

6 0

2 years ago