List and describe 3 conventional heating systems

A 2.0 cm thick brass plate (k_r = 105 W/K-m) is sealed to a glass sheet (kg = 0.80 W/K m), and both have the same area. The expo

astraxan [27]

I need a good phisics teacher for one day online please123

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3 years ago

Example of optical object

Alik [6]

Answer:

Telescope,cameras

Hope it helped

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3 years ago

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An object at rest does not _____ and an object in motion does not _____, unless an _____ force acts upon it

mel-nik [20]

Answer:

An object at rest does not move and an object in motion does not change its velocity, unless an external force acts upon it

Explanation:

This statement is also known as Newton's first law, or law of inertia.

It states that the state of motion of an object can be changed only if there is an external force (different from zero) acting on it: therefore

- If an object is at rest, it will remain at rest if there is no force acting on it

- If an object is moving, it will continue moving at constant velocity if there is no force acting on it

This phenomenon can be also understood by looking at Newton's second law:

F = ma

where

F is the net force on an object

m is the mass

a is the acceleration

If the net force is zero, F = 0, the acceleration of the object is also zero, a = 0: therefore, the velocity of the object does not change, and it will continue moving at the same velocity (which can be zero, if the object was at rest).

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3 years ago

What was the main benefit of scientific management? Select one. a. It proved that horizontal and vertical integration were effec

s2008m [1.1K]

<span>Frederick Winslow Taylor laid down the fundamentals of the scientific managament. The scientific management methods optimized the way tasks were performed, improved economic efficiency, especially labor productivirty and simplified the jobs. The main benefit of this theory of management was that it encouraged workers to create goods more quickly and efficienty. (D)</span>

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3 years ago

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An unmarked police car traveling a constant 38.6 m/s is passed by a speeder traveling 53.4 m/s. Precisely 2.2 seconds after the

Juliette [100K]

Answer:

The unmarked police car needs approximately 71.082 seconds to overtake the speeder.

Explanation:

Let suppose that speeder travels at constant velocity, whereas the unmarked police car accelerates at constant rate. In this case, we need to determine the instant when the police car overtakes the speeder. First, we construct a system of equations:

Unmarked police car

$s = s_{o}+v_{o,P}\cdot (t-t') + \frac{1}{2}\cdot a\cdot (t-t')^{2}$ (1)

Speeder

$s = s_{o} + v_{o,S}\cdot t$ (2)

Where:

$s_{o}$ - Initial position, measured in meters.

$s$ - Final position, measured in meters.

$v_{o,P}$ , $v_{o,S}$ - Initial velocities of the unmarked police car and the speeder, measured in meters per second.

$a$ - Acceleration of the unmarked police car, measured in meters per square second.

$t$ - Time, measured in seconds.

$t'$ - Initial instant for the unmarked police car, measured in seconds.

By equalizing (1) and (2), we expand and simplify the resulting expression:

$v_{o,P}\cdot (t-t')+\frac{1}{2}\cdot a\cdot (t-t')^{2} = v_{o,S}\cdot t$

$v_{o,P}\cdot t -v_{o,P}\cdot t' +\frac{1}{2}\cdot a\cdot t^{2}-a\cdot t'\cdot t+\frac{1}{2}\cdot a\cdot t'^{2} = v_{o,S}\cdot t$

$\frac{1}{2}\cdot a\cdot t^{2}+[(v_{o,P}-v_{o,S})-a\cdot t']\cdot t -\left(v_{o,P}\cdot t'-\frac{1}{2}\cdot a\cdot t'^{2}\right) = 0$

If we know that $a = 1.6\,\frac{m}{s^{2}}$ , $v_{o,P} = 0\,\frac{m}{s}$ , $v_{o,S} = 53.4\,\frac{m}{s}$ and $t' = 2.2\,s$ , then we solve the resulting second order polynomial:

$0.8\cdot t^{2}-56.92\cdot t +3.872 = 0$ (3)

$t_{1} \approx 71.082\,s$ , $t_{2}\approx 0.068$

Please notice that second root is due to error margin for approximations in coefficients. The required solution is the first root.

The unmarked police car needs approximately 71.082 seconds to overtake the speeder.

3 0

3 years ago