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labwork [276]
3 years ago
10

An airplane flies 21 km in 30 minutes. What is its average speed in kilometers per hour?

Physics
2 answers:
Katena32 [7]3 years ago
8 0

Average speed = (distance covered) / (time to cover the distance)

Average speed = (21 km) / (1/2 hour)

Average speed = (21/0.5) (km/hour)

Average speed = 42 km/hr

A very slow airplane !  Maybe an ultralight, a motorized hang-glider, etc.

Citrus2011 [14]3 years ago
7 0
30 minutes is 1/2 of an hour.

So if you just multiplied 21×2, you would get you answer.
The answer is:
42 kilometers per hour
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How does emission spectra occur?
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The frequencies of light that an atom can emit are dependent on states the electrons can be in. When excited, an electron moves to a higher energy level or orbital. When the electron falls back to its ground level the light is emitted.

hope this helped:)

mark brainliest

4 0
3 years ago
6. Applying Explain how scientists see what early galaxies looked like..
svlad2 [7]

Answer:  The younger elliptical and lenticular galaxies had results similar to spiral galaxies like the Milky Way. The researchers found that the older galaxies have a larger fraction of low-mass stars than their younger counterparts.

Explanation:

6 0
2 years ago
An electron is released from rest at the negative plate of a parallel plate capacitor and accelerates to the positive plate (see
mash [69]

Answer:

(7.90 × 10⁻¹⁵) J

Explanation:

The electric force exerted on the elecrron by rhe electric field is given by

F = qE

where |q| = charge on the particle = (1.602 × 10⁻¹⁹) C

E = magnitude of the electric field = (2.9 × 10⁶) V/m or N/C

F = 1.602 × 10⁻¹⁹ × 2.9 × 10⁶ = (4.646 × 10⁻¹³) N

From Newton's first law of motion relation, we can obtain the acceleration this force confers on the electron

F = ma

m = mass of the electron = (9.11 × 10⁻³¹) kg

a = acceleration of the electron caused by the electric force = ?

(4.646 × 10⁻¹³) = (9.11 × 10⁻³¹) × a

a = (4.646 × 10⁻¹³)/(9.11 × 10⁻³¹)

a = (5.10 × 10¹⁷) m/s²

Now, using the equations of motion, we can obtain the velocity with which the electron reaches the positive plate

u = initial velocity of the electron = 0 m/s (since the electron was initially at rest)

v = final velocity of the electron = ?

a = acceleration of the electron = (5.10 × 10¹⁷) m/s²

y = distance covered by the electron = 1.7 cm = 0.017 m

v² = u² + 2ay

v² = 0² + 2(5.10 × 10¹⁷)(0.017)

v² = (1.734 × 10¹⁶)

v = 131,677,182.5 m/s = (1.32 × 10⁸) m/s

Kinetic energy with which the electron hits the positive plate = (1/2)(m)(v²) = (1/2)(9.11 × 10⁻³¹)(1.32 × 10⁸)² = (7.90 × 10⁻¹⁵) J

Hope this Helps!!!

3 0
2 years ago
Why is pure oxygen stored as a liquid under pressure
yKpoI14uk [10]
<h2>Answer: It is highly flammable.</h2>

Explanation:

Liquid oxygen is created from oxygen atoms that have been forced to assume the liquid state due to <u>compression (change of pressure) and temperature modification. </u>

Specifically this is achieved by cooling the oxygen enough to change it to its liquid state. So,<u> as the temperature drops, the atoms move more slowly because they have less energy. </u>

In this sense, in the liquid state it is easier to store and mobilize oxygen, taking into account that it is a highly flammable gas.

3 0
3 years ago
True or false: Balanced forces can change an object's direction?
slava [35]

The statement is false.  Balanced forces can NOT change the speed OR direction of an object's motion.  (See Newton's #1 law of motion.)

4 0
2 years ago
Read 2 more answers
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