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Lana71 [14]
2 years ago
11

A car driving at 20 m/s accelerates continuously 2m/s2​ ​ for 3 seconds. What is its final velocity

Physics
1 answer:
Lesechka [4]2 years ago
5 0

Answer: V= u+ at

V= final velocity

u=initial velocity

a=acceleration

t=time taken

V= 20 + 2*3

V= 26m/s

Explanation:

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a metal sphere with a mass of 90 kg rolls along at 16m/s and strikes a stationary sphere having a mass of 140kg. the first spher
baherus [9]
13.2 meters per second
7 0
3 years ago
Sound waves travel at the rate of 343 m/s at 20°C. If a man standing 450 meters away from the wall of a canyon yells, “Hello,” h
nekit [7.7K]

Answer:

2.62seconds

Explanation:

Speed is defined as the ratio of the distance covered by a body with respect to time.

Speed v = Distance (s)/Time (t)

For a traveling sound wave, the distance between the source of a sound and the reflector is '2S'.

Speed v = 2 × distance (S)/Time (T)

V = 2S/t

2S = vt

Given speed of the wave = 342m/s

Distance covered = 450m

t = 2S/v

t = (2×450)/343

t = 900/343

t = 2.62seconds

It will take him 2.62seconds for him to hear his own voice echo off of the wall.

5 0
2 years ago
Read 2 more answers
Two red and two overlapping balls in the center are surrounded by a green, fuzzy, circular cloud with a white line running throu
PolarNik [594]

Answer:

  • A. The line leading a bracket around the balls, labeled A, represents the nucleus of the atom.

  • B. The white line, labeled B, is signaling the first main energy level, as per the quantum model of the atom.

Explanation:

You are describing the model of an atom with two protons, two neutrons, the electron density (orbital), and two electrons.

Then, you want to know what the <em>labels A</em> and <em>B</em> represent.

The nucleus of the atom is at the center, where protons and neutrons are placed. This is supported by three models: Rutherford's model, Bohr's model, and the (currently accepted) quantum model.

Hence, the red balls and the two overlapping balls in the center are representing the protons and neutrons.

The <em>line leading a bracket around the balls</em>, labeled A, represents the nucleus of the atom, since it is signaling both protons and neutrons in the nucleus.

The green fuzzy circular cloud depicts the region where the electrons are: it is fuzzy in correspondence to the quantum model, which states the electrons are not in a fixed position but in a region around the atom. That region is named orbitals. As per the model you cannot tell the exact position of the electron, and that is what the fuzzy cloud means.

In the the Bohr's model that white line,  which should be circular, where the electrons are, depicts the orbit of the electrons, and the shell, which were idenfified with letters L, M, N, K. The first shell was the L shell.

In the quantum  model, that line corresponds to the principal quantum number n, which is the main energy level. Hence, the line leading to a bracket overlapping the white line depicts the main energy level.

The atom is neutral because it contains the same number of electrons aroud the nucleus as protons inside the nucleus.

3 0
2 years ago
Read 2 more answers
When driving on roads that may be slippery: A. Always drive at the maximum speed limit. B. Use cruise control to maintain a stea
erik [133]

When driving on roads that may be slippery, do not make any sudden changes in speed or direction. Option D is correct.

<h3 /><h3>What is a slippery surface?</h3>

The slick road sign serves as a warning.  When the road is wet or ice, drivers should use extra caution and reduce their speed. When the weather is bad, avoid making any rapid changes in direction.

When driving on roads that may be slippery, do not make any sudden changes in speed or direction. It may cause accident because the vehicle can lose their balance.

Hence, option D is correct.

To learn more about the slippery surface, refer to the link;

brainly.com/question/1953680

#SPJ1

7 0
1 year ago
What is the voltage across a semiconductor bar if the current through it is 0.17 A? The electron concentration in the bar is 2.7
Anastaziya [24]

Answer:

The voltage across a semiconductor bar is 0.068 V.

Explanation:

Given that,

Current = 0.17 A

Electron concentration n= 2.7\times10^{18}\ cm^{-3}

Electron mobility \mu=1000 cm^2/Vs

Length = 0.1 mm

Area = 500 μm²

We need to calculate the resistivity

Using formula of resistivity

\sigma=n\times q\times \mu

\rho=\dfrac{1}{\sigma}

Put the value into the formula

\rho=\dfrac{1}{2.7\times10^{18}\times10^{6}\times1.6\times10^{-19}\times1000\times10^{-4}}

\rho=2\ \mu \Omega m

We need to calculate the resistance

Using formula of resistance

R=\dfrac{\rho l}{A}

R=\dfrac{2\times10^{-6}\times0.1\times10^{-3}}{500\times(10^{-6})^2}

R=0.4\ \Omega

We need to calculate the voltage

Using formula of voltage

V= IR

Put the value into the formula

V=0.17\times0.4

V=0.068\ V

Hence, The voltage across a semiconductor bar is 0.068 V.

6 0
3 years ago
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