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Licemer1 [7]
3 years ago
8

A train rolls past a stationary observer. To him, the train is moving at a speed of 23m/s west, and a woman on the train is movi

ng at a speed of 22.4m/s west. How long does it take the women to move 13 m relative to the train?
A. 24.1s
B.21.7s
C. 23.2s
D. 25.6s
Physics
1 answer:
GREYUIT [131]3 years ago
4 0

Answer:

21.7 seconds.

Explanation:

Woman's velocity relative to train (23 m/s - 22.4 m/s) = 0.6 m/s

Distance woman wants to travel = 13m

To find how long she will take to move 13m relative to the train, take the distance she wants to travel divided by her velocity relative to the train.

(13m)/(0.6 m/s) = 21.6667 seconds or 21.7 seconds.  

Therefore, it will take the woman 21.7 seconds to move 13m.

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Mollie is using springs to hang art projects. She hang a 3.0kg picture on one particular spring and it stretches from 30 cm to 4
fgiga [73]

Spring constant, k = 784 N/m

Distance = 49 cm

<u>Explanation:</u>

Given:

Mass, m₁ = 3 kg

Distance, x₁ = 30 cm

Distance, x₂ = 45 cm

Spring constant, k = ?

(a)

When the mass is being stretched at a height then potential energy gets converted to kinetic energy.

Potential energy = kinetic energy

mgh = \frac{1}{2} k(h-x)^2

On substituting the value, we get:

3 X 9.8 X 0.3 = \frac{1}{2} X k X (0.45 - 0.3)^2\\ \\8.82 = \frac{1}{2} X k X (0.15)^2\\ \\17.64 = k X 0.0225\\\\k = \frac{17.64}{0.0225}\\ \\k = 784 N/m

(b)

Total mass, m = 3 kg + 2kg

                       = 5 kg

Distance, x = ?

We know:

Force = mg

Force on a spring = kx

mgh = \frac{1}{2}k (x - h)^2

5 X 9.8 X 0.3 = \frac{1}{2} X 784 X (x - 0.3)^2\\\\14.7 = 392 (x - 0.3)^2\\\\0.0375 = ( x - 0.3)^2\\\\0.194 = x - 0.3\\\\x = 0.494 m

The spring stretches to 0.494m or 49 cm when a weight of 2kg is added

8 0
3 years ago
If the released energy of one earthquake is 100 times that of another, how much greater is its magnitude on the richter scale?
Alekssandra [29.7K]
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3 years ago
why should scientists write reports and give oral presentations of the steps and results of their in investigations?
Goshia [24]
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A woman is standing in the ocean, and she notices that after a wave crest passes by, five more crests pass in a time of 50.2 s.
lorasvet [3.4K]

Explanation:

(a) The period of a wave is the time required for one complete cycle. In this case, we have the time of five cycles. So:

T=\frac{t}{n}\\\\T=\frac{50.2s}{5}\\T=10.04s

(b) The frequency of a wave is inversely proportional to its period:

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(c) The wavelength is the distance between two successive crests, so:

\lambda=30.2m

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