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3 years ago

A man walks 30 m to the west than 5 m to the east in 45 seconds.

Physics

1 answer:

harkovskaia [24]3 years ago

4 0

Answer:

35 m

0.56 m/s west

Explanation:

A) Total distance is the length of the path taken.

30 m + 5 m = 35 m

B) Velocity is displacement over time. Displacement is the difference between the final position and the initial position.

If west is -x, and east is +x, then:

Δx = -30 m + 5 m

Δx = -25 m

v = Δx / t

v = -25 m / 45 s

v = -0.56 m/s

v = 0.56 m/s west

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Alligators and other reptiles don't use enough metabolic energy to keep their body temperatures constant. they cool off at night

drek231 [11]

To compute for the heat, $Q$ needed to be absorbed or released, we need

$Q = mc\Delta T$

where $m$ is the mass of the alligator, $\Delta T$ is the change in temperature, and $c$ is the specific heat of the alligator's body. Plugging in all the information we have,

$Q = (300 kg)(3400 kJ/K)(30-25) = 5100000 J$

Recall that 1 Watt = 1 J/s, thus time needed to absorb radiation from the sun is

$t = \frac{Q}{W}\\ t = 4250 seconds$

That means it takes 4250 seconds for the alligator to warm up to be able to absorb the radiation from the sun.

Answer: 4250 seconds

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4 years ago

A janitor standing on the top floor of a building wishes to determine the depth of the elevator shaft. They drop a rock from res

Bumek [7]

Answer:

Part a)

H = 26.8 m

Part b)

error = 7.18 %

Explanation:

Part a)

As the stone is dropped from height H then time taken by it to hit the floor is given as

$t_1 = \sqrt{\frac{2H}{g}}$

now the sound will come back to the observer in the time

$t_2 = \frac{H}{v}$

so we will have

$t_1 + t_2 = 2.42$

$\sqrt{\frac{2H}{g}} + \frac{H}{v} = 2.42$

so we have

$\sqrt{\frac{2H}{9.81}} + \frac{H}{336} = 2.42$

solve above equation for H

$H = 26.8 m$

Part b)

If sound reflection part is ignored then in that case

$H = \frac{1}{2}gt^2$

$H = \frac{1}{2}(9.81)(2.42^2)$

$H = 28.7 m$

so here percentage error in height calculation is given as

$percentage = \frac{28.7 - 26.8}{26.8} \times 100$

$percentage = 7.18$

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3 years ago

An electric motor in a hair dryer is running at its normal constant operating speed and, thus, is drawing a relatively small cur

svlad2 [7]

Answer:

The temperature of the coil will increase (over heating will occur)

Explanation:

This overheating generally occurs when the motor is overloaded, when a bearing seizes up, when something locks the motor shaft and prevents it from turning, or when the motor simply fails to start properly.

Back emf is zero when the motor is not turning, and it increases proportionally to the motor's angular velocity. As the motor turns faster and faster, the back emf grows, always opposing the driving emf, and reduces the voltage across the coil and the amount of current it draws.

3 0

3 years ago

Brainliest if correct Question 2 of 10

Troyanec [42]

Answer:

b and d

Explanation:

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3 years ago

Which Lewis dot diagram shows an atom that needs 2 more electrons in its outermost shell?

sergiy2304 [10]

Answer: Option (c) is the correct answer.

Explanation:

Atomic number of hydrogen is 1 and one dot in its lewis structure displays only one electron. So, in order to complete its octet it needs one more electron.

Atomic number of carbon is 6 and its electronic distribution is 2, 4. Carbon needs 4 more electrons in order to complete its octet.

Atomic number of oxygen is 8 and its electronic distribution is 2, 6. In order to complete octet, oxygen needs 2 more electrons.

Atomic number of fluorine is 9 and its electronic distribution is 2, 7. In order to complete octet, fluorine needs 1 more electron.

Hence, we can conclude that out of the given options, lewis dot structure of oxygen atom needs 2 more electrons in its outermost shell.

8 0

4 years ago

Read 2 more answers