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3 years ago

14

You watch distant Sally Homemaker driving nails into a front porch at a regular rate of 1 stroke per second. You hear the sound

of the blows exactly synchronized with the blows you see. And then you hear one more blow after you see the hammering stop. How far away is she?

1 answer:

denpristay [2]3 years ago

6 0

Answer: 343meters away

Explanation:

The velocity of sound in air is approx 343m/s

SO,

Velocity = distance/time taken.

The time taken is 1second only.

Distance = velocity × time

Distance = 343 × 1 = 343meters.

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Which best describes two counteracting forces on an object

Natali5045456 [20]

The correct answer is B two children pulling apart a wishbone

Let me know if you have any questions, and have a nice day!

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Which of these is a chemical control used to help control invasive species?

astraxan [27]

Answer:

a

Explanation:

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3 years ago

A 1.60 m cylindrical rod of diameter 0.550 cm is connected to a power supply that maintains a constant potential difference of 1

bija089 [108]

1.

Answer:

Part a)

$\rho = 1.35 \times 10^{-5}$

Part b)

$\alpha = 1.12 \times 10^{-3}$

Explanation:

Part a)

Length of the rod is 1.60 m

diameter = 0.550 cm

now if the current in the ammeter is given as

$i = 18.7 A$

V = 17.0 volts

now we will have

$V = I R$

$17.0 = 18.7 R$

R = 0.91 ohm

now we know that

$R = \rho \frac{L}{A}$

$0.91 = \rho \frac{1.60}{\pi(0.275\times 10^{-2})^2}$

$\rho = 1.35 \times 10^{-5}$

Part b)

Now at higher temperature we have

$V = I R$

$17.0 = 17.3 R$

R = 0.98 ohm

now we know that

$R = \rho \frac{L}{A}$

$0.98 = \rho' \frac{1.60}{\pi(0.275\times 10^{-2})^2}$

$\rho' = 1.46 \times 10^{-5}$

so we will have

$\rho' = \rho(1 + \alpha \Delta T)$

$1.46 \times 10^{-5} = 1.35 \times 10^{-5}(1 + \alpha (92 - 20))$

$\alpha = 1.12 \times 10^{-3}$

2.

Answer:

Part a)

$i = 1.55 A$

Part b)

$v_d = 1.4 \times 10^{-4} m/s$

Explanation:

Part a)

As we know that current density is defined as

$j = \frac{i}{A}$

now we have

$i = jA$

Now we have

$j = 1.90 \times 10^6 A/m^2$

$A = \pi(\frac{1.02 \times 10^{-3}}{2})^2$

so we will have

$i = 1.55 A$

Part b)

now we have

$j = nev_d$

so we have

$n = 8.5 \times 10^{28}$

$e = 1.6 \times 10^{-19} C$

so we have

$1.90 \times 10^6 = (8.5 \times 10^{28})(1.6 \times 10^{-19})v_d$

$v_d = 1.4 \times 10^{-4} m/s$

8 0

3 years ago

An Olympic runner completes the 200-meter sprint in 23 seconds. What is the runner’s average speed? (Round your answer to the ne

LUCKY_DIMON [66]

The answer that is got 8.7 . I got that because if you divide 200 by 23 you get <span>8.69565217391 and if you round that you get 8.7</span>

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5. A box weighs 196 N. A rope is tied to the box. What is the

natta225 [31]

Answer:

296 N

Explanation:

Draw a free body diagram. The box has two forces on it: tension up and weight down.

Apply Newton's second law:

∑F = ma

T − mg = ma

T = m (g + a)

Given m = 196 N / 9.8 m/s² = 20 kg, and a = +5 m/s²:

T = (20 kg) (9.8 m/s² + 5 m/s²)

T = 296 N

5 0

3 years ago