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3 years ago

Which best describes most covalent compounds? resilient brittle cold warm

Physics

2 answers:

DerKrebs [107]3 years ago

8 0

Answer:

B.)

Explanation:

The atoms can be of the same element or different elements. In each molecule, the bonds between the atoms are strong but the bonds between molecules are usually weak. This makes many solid materials with covalent bonds brittle.

Ugo [173]3 years ago

4 0

Answer:

B) brittle

Explanation:

This describes most covalent compounds.

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3 years ago

An electric motor rotating a workshop grinding wheel at a rate of 1.31 ✕ 102 rev/min is switched off. Assume the wheel has a con

antoniya [11.8K]

(a) 4.03 s

The initial angular velocity of the wheel is

$\omega_i = 1.31 \cdot 10^2 \frac{rev}{min} \cdot \frac{2\pi rad/rev}{60 s/min}=13.7 rad/s$

The angular acceleration of the wheel is

$\alpha = -3.40 rad/s^2$

negative since it is a deceleration.

The angular acceleration can be also written as

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

where

$\omega_f = 0$ is the final angular velocity (the wheel comes to a stop)

t is the time it takes for the wheel to stop

Solving for t, we find

$t=\frac{\omega_f - \omega_i }{\alpha}=\frac{0-13.7 rad/s}{-3.40 rad/s^2}=4.03 s$

(b) 27.6 rad

The angular displacement of the wheel in angular accelerated motion is given by

$\theta= \omega_i t + \frac{1}{2}\alpha t^2$

where we have

$\omega_i=13.7 rad/s$ is the initial angular velocity

$\alpha = -3.40 rad/s^2$ is the angular acceleration

t = 4.03 s is the total time of the motion

Substituting numbers, we find

$\theta= (13.7 rad/s)(4.03 s) + \frac{1}{2}(-3.40 rad/s^2)(4.03 s)^2=27.6 rad$

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3 years ago

You've learned about simple circuits and resistors at this point. So, let's talk about how we can power different circuits. Supp

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Answer:

Explanation:

Total resistance of 2 bulb in series

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current in each bulb

= 9/200 = .045 A

In case of parallel combination of bulb

total resistance

= 100 x 100 / (100+100)

50 ohm

current in the main circuit

= 9 / 50 A

current in each bulb

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.09

So in the second case current is more , hence heat generated too will be more . So brightness too will be more.

First set ( in series ) will be dimmer.

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3 years ago

A ballast is dropped from a stationary hot-air balloon that is at an altitude of 576 ft. Find (a) an expression for the altitude

Nadya [2.5K]

Answer:

Explanation:

If a ball dropped from a stationary hot-air balloon that is at an altitude of 576 ft, an expression for the altitude of the ballast after t seconds can be expressed using the equation of motion;

$S = ut + \frac{1}{2}at^{2}$

S is the altitude of the ballest

u is the initial velocity

a is the acceleration of the body

t is the time taken to strike the ground

Since the body is dropped from a stationary air balloon, the initial velocity u will be zero i.e u = 0m/s

Also, since the ballast is dropped from a stationary hot-air balloon, the body is under the influence of gravity, the acceleration will become acceleration due to gravity i.e a = +g

Substituting this values into the equation of the motion;

$S = 0 + \frac{1}{2}gt^2\\ S = \frac{1}{2}gt^2\\$

a) An expression for the altitude of the ballast after t seconds is therefore

$S = \frac{1}{2}gt^2\\$

b) Given S = 576ft and g = 32ft/s², substituting this into the formula in (a);

$576 = \frac{1}{2}(32)t^2\\\\\\576*2 = 32t^2\\1152 = 32t^2\\t^2 = \frac{1152}{32} \\t^2 = 36\\t = \sqrt{36}\\ t = 6.0secs$

This means that the ballast strikes the ground after 6secs

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v = 0 + 32(6)

v = 192ft

7 0

4 years ago

The compressor of an air conditioner draws an electric current of 23.7 A when it starts up. If the start-up time is 2.35 s long,

defon

Answer:

Electric charge, Q = 55.69 C

Explanation:

It is given that,

Electric current drawn by the compressor, I = 23.7 A

Time taken, t = 2.35 s

We need to find the electric charge passes through the circuit during this period. The definition of electric current is given by total charge divided by total time taken.

$I=\dfrac{q}{t}$

Where,

q is the electric charge

$q=I\times t$

$q=23.7\ A\times 2.35\ s$

q = 55.69 C

So, the electric charge passes through the circuit during this period is 55.69 C. Hence, this is the required solution.

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3 years ago