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3 years ago

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A car drives to the east in a time of 4 hours. Then, immediately (not realistic, but just assume this is the case for this probl

em), travels 12 km to the west in 4 hours. The average speed for the entire trip is 5 km/hr. What is the average speed of the car for the first part of the trip, in km/hr, while the car was traveling east?

1 answer:

diamong [38]3 years ago

4 0

Answer:

Average speed in east direction $speed=\frac{distance}{time}=\frac{28}{4}=7km/hr$

Explanation:

We have given average speed of the entire trip = 5 km/hr

First the car 4 hours then travels 12 km in 4 hours

So total time of the trip = 4+4 = 8 hours

So total distance traveled in the trip $d=speed\times time = 5\times 8=40km$

As the car travel 12 km in 4 hours to the west

So distance traveled in 4 hour in east = 40 -12 = 28 km

Time in east direction = 4 hour

So average speed in east direction $speed=\frac{distance}{time}=\frac{28}{4}=7km/hr$

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Recall that impulse = momentum (FAt = Ap and that Ap is just mx v). How long (time) must a group of people pull with a force of

elixir [45]

The time taken for the group of people to pull the car, giving it a velocity of 1.5 m/s is 3.75 s

Momentum is simply defined as the product of mass and velocity i.e

Momentum = mass × velocity

To answer the question given, we'll begin by calculating the change in momentum. This can be obtained as follow:

Mass = 1500 Kg

Initial velocity (u) = 0 m/s

Final velocity (v) = 1.5 m/s

<h3>Change in momentum =? </h3>

Change in momentum = m(v – u)

Change in momentum = 1500 (1.5 – 0)

Change in momentum = 1500 × 1.5

<h3>Change in momentum = 2250 Kg•m/s</h3>

Finally, we shall determine the time

Change in momentum = 2250 Kg•m/s

Force (F) = 600 N

<h3>Time (t) =? </h3>

Impulse = Ft = change in momentum

FT = change in momentum

600 × t = 2250

Divide both side by 600

t = 2250 / 600

<h3>t = 3.75 s</h3>

Thus, the time required is 3.75 s

Learn more on momentum and impulse: brainly.com/question/14486244

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2 years ago

Compare the freezing point of water in the aquanaut’s apartment to its value at the surface. Is it higher, lower, or the same?

Lelu [443]

Answer:

Freezing Point - Lower

Boiling Point - Higher

Solid- liquid transition line in the phase diagram has a negative slope, but the liquid-gas transition line has a positive slope. Since there is more air pressure at 100m it will take less to freeze the water but more to boil it since it requires a larger temperature under larger pressures

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3 years ago

An airplane flew 1000 m in 400 seconds. What is the airplane's speed?

weqwewe [10]

Answer:

$speed = \frac{distance}{time} \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = \frac{1000}{400} \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 2.5m {s}^{ - 1}$

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3 years ago

Read 2 more answers

A solid brass cylinder and a solid wood cylinder have the same radius and mass (the wood cylinder is longer). Released together

Lena [83]

Answer:

a. They will be tie

b. Win the wood cylinder

Explanation:

a.

The both cylinders will reach the bottom at the same time notice the relation in the equation in indepent of the length and both have the same radius and the same rotational inertia.

$I=\frac{1}{2}*m*r^2$

$a=\frac{g*sin(\beta)}{1+I_{com}/m*r^2}$

So both will be tie

b.

$a_{brass}=\frac{g*sin(\beta)}{1+I_{brass}/m*r^2}=a_{wood}=\frac{g*sin(\beta)}{1+I_{wood}/m*r^2}$

The acceleration of the wood cylinder is larger than the acceleration of the brass cylinder so the cylinder of wood will reach the bottom first

$a_{brass}$

So the wood win the race

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3 years ago

One string of a certain musical instrument is 70.0 cm long and has a mass of 8.79 g . It is being played in a room where the spe

Svetach [21]

To solve this problem we will apply the concepts of linear mass density, and the expression of the wavelength with which we can find the frequency of the string. With these values it will be possible to find the voltage value. Later we will apply concepts related to harmonic waves in order to find the fundamental frequency.

The linear mass density is given as,

$\mu = \frac{m}{l}$

$\mu = \frac{8.79*10^{-3}}{70*10^{-2}}$

$\mu = 0.01255kg/m$

The expression for the wavelength of the standing wave for the second overtone is

$\lambda = \frac{2}{3} l$

Replacing we have

$\lambda = \frac{2}{3} (70*10^{-2})$

$\lambda = 0.466m$

The frequency of the sound wave is

$f_s = \frac{v}{\lambda_s}$

$f_s = \frac{344}{0.768}$

$f_s = 448Hz$

Now the velocity of the wave would be

$v = f_s \lambda$

$v = (448)(0.466)$

$v = 208.768m/s$

The expression that relates the velocity of the wave, tension on the string and linear mass density is

$v = \sqrt{\frac{T}{\mu}}$

$v^2 = \frac{T}{\mu}$

$T= \mu v^2$

$T = (0.01255kg/m)(208.768m/s)^2$

$T = 547N$

The tension in the string is 547N

PART B) The relation between the fundamental frequency and the $n^{th}$ harmonic frequency is

$f_n = nf_1$

Overtone is the resonant frequency above the fundamental frequency. The second overtone is the second resonant frequency after the fundamental frequency. Therefore

$n=3$

Then,

$f_3 = 3f_1$

Rearranging to find the fundamental frequency

$f_1 = \frac{f_3}{3}$

$f_1 = \frac{448Hz}{3}$

$f_1 = 149.9Hz$

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3 years ago