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3 years ago

Why is it important to use constants in an experiment?

1 answer:

5 0

<span>In order for the results to be valid, the dependent variable can only be affected by the independent variable, so somethings need to be kept constant. The things that need to be kept constant are called controlled variables.</span>

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Why is wood a renewable resource?

sweet-ann [11.9K]

Answer:

Trees grow everywhere, so we always have some

Explanation:

Wood is a renewable resource; trees can be replanted and grown to maturity in place of those that are cut down. As long as the trees are replanted at the same rate as they are cut down wood will be a renewable resource.

6 0

2 years ago

Which statement BEST describes the benefits of muscular fitness training?

Maru [420]

Whatever the statement is, I know one thing for sure: It's NOT included on the list of choices that you've provided.

6 0

2 years ago

How much power is used by a hair dryer if it does 40,000 J of work in 40 seconds?

bearhunter [10]

Answer:

40000÷40=1000 joules is required to work in 40 seconds

6 0

3 years ago

Match the indices of refraction with the corresponding effects on the waves.

Yanka [14]

Answer:

B) waves speed up

C) waves bend away from the normal

Explanation:

The index of refraction of a material is the ratio between the speed of light in a vacuum and the speed of light in that medium:

$n=\frac{c}{v}$

where

c is the speed of light in a vacuum

v is the speed of light in the medium

We can re-arrange this equation as:

$v=\frac{c}{n}$

So from this we already see that if the index of refraction is lower, the speed of light in the medium will be higher, so one correct option is

B) waves speed up

Moreover, when light enters a medium bends according to Snell's Law:

$n_1 sin \theta_1 = n_2 sin \theta_2$

where

$n_1 ,n_2$ are the index of refraction of the 1st and 2nd medium

$\theta_1,\theta_2$ are the angles made by the incident ray and refracted ray with the normal to the interface

We can rewrite the equation as

$sin \theta_2 = \frac{n_1}{n_2}sin \theta_1$

So we see that if the index of refraction of the second medium is lower ( $n_2$ ), then the ratio $\frac{n_1}{n_2}$ is larger than 1, so the angle of refraction is larger than the angle of incidence:

$\theta_2>\theta_1$

This means that the wave will bend away from the normal. So the other correct option is

C) waves bend away from the normal

3 0

3 years ago

Frank stands still while throwing a dart toward a target with a speed of 25 m/s.

fgiga [73]

ANSWER IS A)

THE SPEED IS 25 M/S FOR BOTH PEOPLE

9 0

2 years ago