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3 years ago

Which evidence best supports the theory that the universe began with a massive explosion?

2 answers:

8 0

Evidence isn't used to support theories. Theories are attempts to explain evidence. The so-called "big bang theory" is able to explain the origin of the cosmic background radiation.

Ivanshal [37]3 years ago

5 0

I think it's b. But I'm not sure

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An Earth satellite is in a circular orbit at an altitude of 500 km.

Dafna1 [17]

Answer:

Speed Unchanged.

Explanation:

As work is defined as a product of force over a distance. If the distance in altitude is constant = 500km, there's 0 change in distance and force, no work would be done by the gravitational force.

Since potential energy of the satellite is unchanged, unless there's additional internal energy source, the kinetic energy would remain unchanged, so would its speed.

8 0

3 years ago

Starting from rest, a 2.3x10-4 kg flea springs straight upward. While the flea is pushing off from the ground, the ground exerts

Harman [31]

Answer:

3.13 m/s

Explanation:

From the question,

Since the flea spring started from rest,

Ek = W................... Equation 1

Where Ek = Kinetic Energy of the flea spring, W = work done on the flea spring.

But,

Ek = 1/2mv²............ Equation 2

Where m = mass of the flea spring, v = flea's speed when it leaves the ground.

substitute equation 2 into equation 1

1/2mv² = W.................... Equation 3

make v the subject of the equation

v = √(2W/m)................. Equation 4

Given: W = 3.6×10⁻⁴ J, m = 2.3×10⁻⁴ kg

Substitute into equation 4

v = √[2×3.6×10⁻⁴ )/2.3×10⁻⁴]

v = 7.2/2.3

v = 3.13 m/s

Hence the flea's speed when it leaves the ground = 3.13 m/s

4 0

3 years ago

The elements selenium and oxygen are both poor electrical conductors. In which section of the periodic table are they

murzikaleks [220]

Answer:

The answer to your question is Nonmetals

Explanation:

Nonmetals they are bad conductors of heat and electricity except graphite.

Metalloids they are less conductors of electricity than metals.

Noble gases they conduct electricity.

Halogens they are not metals and do not conduct electricity.

From this information, we conclude that Oxygen and Selenium are nonmetals.

6 0

3 years ago

What is an non-example of a switch

loris [4]

Dont really understand what youre asking but switches can be used to turn things on and off.

3 0

3 years ago

When the electron in a hydrogen atom moves from n = 6 to n = 1, light with a wavelength of ________ nm is emitted?

Oduvanchick [21]

First we find the energy level with the following formula, where a is the energy level, n1 is the final energy level, n2 is the starting energy level and r is Rydberg's constant in Joules
$a = r \times ( \frac{1}{n1} - \frac{1}{n2} )$
We insert the values

$a = 2.18 \times {10}^{ - 18} \times ( \frac{1}{ {1}^{2} } - \frac{1}{ {6}^{2} } )$
$= 2.12 \times {10}^{ - 18}$
The wavelength is found with this formula, where h is Planck's constant and c is the speed of light
$wavelength = \frac{h \times c}{a}$
Finally we insert the values
$\frac{6.626 \times {10}^{ - 34} \times 3 \times {10}^{8} }{2.12 \times {10}^{ - 18} } = 9.376 \times {10}^{ - 8}$
Which is the same as 93.8 nm

3 0

3 years ago