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3 years ago

12

The safe load for a certain horizontal beam used to hold up part of a building varies inversely as the length between the suppor

ts. True False

1 answer:

ryzh [129]3 years ago

7 0

Answer:

The answer is true.

Explanation:

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Thermal energy depends on an object’s

oee [108]

The correct answer is D. I alread took this test.

4 0

3 years ago

Read 2 more answers

A disk rotates about its central axis starting from rest and accelerates with constant angular acceleration. At one time it is r

atroni [7]

(a) $2.79 rev/s^2$

The angular acceleration can be calculated by using the following equation:

$\omega_f^2 - \omega_i^2 = 2 \alpha \theta$

where:

$\omega_f = 20.0 rev/s$ is the final angular speed

$\omega_i = 11.0 rev/s$ is the initial angular speed

$\alpha$ is the angular acceleration

$\theta=50.0 rev$ is the number of revolutions made by the disk while accelerating

Solving the equation for $\alpha$ , we find

$\alpha=\frac{\omega_f^2-\omega_i^2}{2d}=\frac{(20.0 rev/s)^2-(11.0 rev/s)^2}{2(50.0 rev)}=2.79 rev/s^2$

(b) 3.23 s

The time needed to complete the 50.0 revolutions can be found by using the equation:

$\alpha = \frac{\omega_f-\omega_i}{t}$

where

$\omega_f = 20.0 rev/s$ is the final angular speed

$\omega_i = 11.0 rev/s$ is the initial angular speed

$\alpha=2.79 rev/s^2$ is the angular acceleration

t is the time

Solving for t, we find

$t=\frac{\omega_f-\omega_i}{\alpha}=\frac{20.0 rev/s-11.0 rev/s}{2.79 rev/s^2}=3.23 s$

(c) 3.94 s

Assuming the disk always kept the same acceleration, then the time required to reach the 11.0 rev/s angular speed can be found again by using

$\alpha = \frac{\omega_f-\omega_i}{t}$

where

$\omega_f = 11.0 rev/s$ is the final angular speed

$\omega_i = 0 rev/s$ is the initial angular speed

$\alpha=2.79 rev/s^2$ is the angular acceleration

t is the time

Solving for t, we find

$t=\frac{\omega_f-\omega_i}{\alpha}=\frac{11.0 rev/s-0 rev/s}{2.79 rev/s^2}=3.94 s$

(d) 21.7 revolutions

The number of revolutions made by the disk to reach the 11.0 rev/s angular speed can be found by using

$\omega_f^2 - \omega_i^2 = 2 \alpha \theta$

where:

$\omega_f = 11.0 rev/s$ is the final angular speed

$\omega_i = 0 rev/s$ is the initial angular speed

$\alpha=2.79 rev/s^2$ is the angular acceleration

$\theta=?$ is the number of revolutions made by the disk while accelerating

Solving the equation for $\theta$ , we find

$\theta=\frac{\omega_f^2-\omega_i^2}{2\alpha}=\frac{(11.0 rev/s)^2-0^2}{2(2.79 rev/s^2)}=21.7 rev$

4 0

2 years ago

A flat, wide cloud floats horizontally a few kilometers above the surface of Earth. Its lower surface carries a uniform surface

valentinak56 [21]

Answer:

$\frac{kQ}{r^2} r^$

Explanation:

Electric field strength= Force/unit charge

E= (kQq/r²)/q ₓ r

where r is the unit vector in the direction of unit charge

E= $\frac{kQ}{r^2} r^$

4 0

2 years ago

Which quantum number gives the approximate energy of an electron in the quantum mechanical model of the atom? A) n B) I C) m1 D

alexdok [17]

Answer:

Option A) n

Explanation:

In accordance to Quantum Mechanical model of an atom:

The Principle Quantum number (n) gives the description of the shell of an electron and the energy level of an electron in an atom.
The angular momentum also referred to as Azimuthal Quantum number (l) gives the description of the shape of the orbitals and helps in determination of angular momentum magnitude.
The magnetic quantum number ( $m_{1}$ ) describes the energy levels or the number of orbitals contained in a subshell and the way these are oriented within.

The spin quantum no. ( $m_{2}$ ) determines the elelctron spin's direction which may be ( $-\frac{1}{2}$ ) or ( $+\frac{1}{2}$ ).

4 0

2 years ago

What is the name of the element with 83 protons and 80 electrons?

dmitriy555 [2]

An element with 83 protons has the atomic number 83. If you look at a periodic table you will see Bismuth is the element with the atomic number of 83. It will have a positive charge of +3 because it has only 80 electrons and 83protons. 83-80=+3.

8 0

3 years ago