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3 years ago

All object changes are compared with a ____ , which is an object that appears to stay in place?

Physics

1 answer:

Kaylis [27]3 years ago

8 0

Answer:

All object changes are compared with a <em>reference</em> , which is an object that appears to stay in place.

Explanation:

In scientific experiments, the changes in the experimental object are observed by comparing the changes with a reference object. In the reference object, no changes are made and conditions are kept normal in it. For example, if we want to measure the distance of two cars from a point, the point will be the reference point from which the distance shall be measured. Hence, all changes are made by comparison from a reference object or point.

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A motorcycle and a police car are moving toward one another. The police car emits sound with a frequency of 523 Hz and has a spe

Firdavs [7]

To solve this problem it is necessary to apply the concepts related to Dopler's Law. Dopler describes the change in frequency of a wave in relation to that of an observer who is in motion relative to the Source of the Wave.

It can be described as

$f = \frac{c\pm v_r}{c\pm v_s}f_0$

c = Propagation speed of waves in the medium

$v_r$ = Speed of the receiver relative to the medium

$v_s$ = Speed of the source relative to the medium

$f_0 =$ Frequency emited by the source

The sign depends on whether the receiver or the source approach or move away from each other.

Our values are given by,

$v_s = 32.2m/s \rightarrow$ Velocity of car

$v_r = 14.8 m/s \rightarrow$ velocity of motor

$c = 343m/s \rightarrow$ Velocity of sound

$f_0 = 523Hz \rightarrow$ Frequency emited by the source

Replacing we have that

$f = \frac{c + v_r}{c - v_s}f_0$

$f = \frac{343 + 14.8}{343 - 32}(523)$

$f = 601.7Hz$

Therefore the frequency that hear the motorcyclist is 601.7Hz

8 0

3 years ago

A constant force of 45 N directed at angle θ to the horizontal pulls a crate of weight 100 N from one end of a room to another a

Rasek [7]

Answer:

$W=173.48J$

Explanation:

information we know:

Total force: $F=45N$

Weight: $w=100N$

distance: $4m$

vertical component of the force: $F_{y}=12N$

-------------

In this case we need the formulas to calculate the components of the force (because to calculate the work we need the horizontal component of the force).

horizontal component: $F_{x}=Fcos\theta$

vertical component: $F_{y}=Fsen\theta$

but from the given information we know that $F_{y}=12N$

so, equation these two $F_{y}=Fsen\theta$ and $F_{y}=12N$

$Fsen\theta =12N$

and we know the force $F=45N$ , thus:

$45sen\theta=12$

now we clear for $\theta$

$sen\theta =12/45\\\theta=sin^{-1}(12/45)\\\theta =15.466$

the angle to the horizontal is 15.466°, with this information we can calculate the horizontal component of the force:

$F_{x}=Fcos\theta$

$F_{x}=45cos(15.466)\\F_{x}=43.37N$

whith this horizontal component we calculate the work to move the crate a distance of 4 m:

$W=F_{x}*D\\W=(43.37N)(4m)\\W=173.48J$

the work done is W=173.48J

7 0

3 years ago

Wнιcн deмonѕтraтeѕ condυcтιon

jekas [21]

C.) cool feet walking across a hot pavement.

The reason because the other ones deals with radiation. Only C.) is the right answer because the feet is touching the hot pavement which is conduction.

3 0

3 years ago

0.250 moles of gas are in a piston.The gas does 109 J of work while 240 J of heat are added. What is the change in internal ener

irina [24]

Answer:

+131Joules

Explanation:

Energy can be expressed using below expresion.

ΔE = (q + w).........eqn(1)

q will be + be if heat is gained hence, q= 240 J

work "w" will be - ve if work is done by the system, hence w= -109 J

Then substitute into eqn(1)

Change in Internal energy=

= (240 -109 )

= +131J

6 0

3 years ago

Showing results for a 4 olm and 8 ohm resistor are connected in series. The current through the 4 olm resistor is 2 amps. What i

kirill115 [55]

Answer:

Let R1= resistance of 4ohms

R2= resistance of 8ohms

Equivalent resistance R will be

R=R1 + R2

=> 4+8=12ohms

The current through the two resistors will be the same since they are connected in series. Notwithstanding, the voltage will drop to appreciate the change.

Explanation:

7 0

3 years ago