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3 years ago

Can I get some help please? Thanks!

Physics

1 answer:

Brums [2.3K]3 years ago

5 0

To begin with it was believed that light transmitted instantaneously. However now we know that light just moved to fast to be seen.
The first successful measurement was in 1676, by a man named Roemer. He came up with a measurement that light moved a 214,000 km/s. Which was a very approximate evaluation.
Another measurement was obtained in 1728, by a man named James Bradley, he came up with his measurement by observing stellar aberrations. He came up with a value of 301,000 km/s.
In 1849 Fizeau, he used a beam of light and a mirror, he got a value of 315,000 km/s. Foucault improved this measurement a year later, using rotating mirrors he got a more accurate value of 298,000 km/s.

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HELP ASAP!!! The gravitational pull of the Moon is much less than the

katovenus [111]

Answer:

I'm pretty sure its B and C

Explanation:

B bc the weight is gravitational pull x mass so when the object has same mass the weight is smaller on moon

C bc mass is the same - you can't change it

7 0

3 years ago

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When a surfer rides an ocean wave on her surfboard, she is actually riding on. A. a crest that is toppling over. . B. a trough o

ruslelena [56]

The right answer to this question is A. a crest that is toppling over. When a surfer rides an ocean wave on her surfboard, she is actually riding on a crest. The crest is the point on a wave with the maximum value or upward displacement within a cycle.

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3 years ago

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A 30-cm long string, with one end clamped and the other free to move transversely, is vibrating in its second harmonic. The wave

Ann [662]

Answer:

$\lambda$ = 40 cm

Explanation:

given data

string length = 30 cm

solution

we take here equation of length that is

L = $n \times \frac{1}{4} \lambda$ ...............1

total length will be here

$L = \frac{\lambda}{2} + \frac{\lambda}{4}\\$

$L = \frac{3 \lambda }{4}$

so $\lambda$ will be

$\lambda = \frac{4L}{3}\\\lambda = \frac{4\times 30}{3}$

$\lambda$ = 40 cm

5 0

3 years ago

A spinning ice skater will speed up if he brings his arms close to his body. Which of the following statements explains this phe

xxMikexx [17]

A. Angular momentum is always conserved would be the correct answer.

This is because like linear momentum (mvmv), angular momentum (r×mvr×mv) is a conserved quantity, where rr is the vector from the center of rotation. For a skater holding a static pose, for each particle making up her body, the contribution in magnitude to the total angular momentum is given by mirivimirivi. Thus bringing in her arms reduces riri for those particles. In order to conserve angular momentum, there is then an increase in the angular velocity.

hope this helps!

7 0

3 years ago

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Example 3 :

kherson [118]

The friction factor and head loss when velocity is 1m/s is 0.289 and 1.80 × 10^8 respectively. Also, the friction factor and head loss when velocity is 3m/s is 0.096 and 5.3 × 10^8 respectively.

<h3>How to determine the friction factor</h3>

Using the formula

μ = viscosity = 0. 06 Pas

d = diameter = 120mm = 0. 12m

V = velocity = 1m/s and 3m/s

ρ = density = 0.9

a. Velocity = 1m/s

friction factor = 0. 52 × $\frac{0. 06}{0. 12* 1* 0. 9}$

friction factor = 0. 52 × $\frac{0. 06}{0. 108}$

friction factor = 0. 52 × 0. 55

friction factor $= 0. 289$

b. When V = 3mls

Friction factor = 0. 52 × $\frac{0. 06}{0. 12 * 3* 0. 9}$

Friction factor = 0. 52 × $\frac{0. 06}{0. 324}$

Friction factor = 0. 52 × 0. 185

Friction factor $= 0.096$

Loss When V = 1m/s

Head loss/ length = friction factor × 1/ 2g × velocity^2/ diameter

Head loss = 0. 289 × $\frac{1}{2*6. 6743 * 10^-11}$ × $\frac{1^2}{0. 120}$ × $\frac{1}{100}$

Head loss = 1. 80 × 10^8

Head loss When V = 3m/s

Head loss = $0. 096$ × $\frac{1}{1. 334 *10^-10}$ × $\frac{3^2}{0. 120}$ × $\frac{1}{100}$

Head loss = 5. 3× 10^8

Thus, the friction factor and head loss when velocity is 1m/s is 0.289 and 1.80 ×10^8 respectively also, the friction factor and head loss when velocity is 3m/s is 0.096 and 5.3 ×10^8 respectively.

Learn more about friction here:

brainly.com/question/24338873

#SPJ1

4 0

2 years ago