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3 years ago

The American Psychological Association is the only organization that can approve psychological research studies.

Physics

1 answer:

pav-90 [236]3 years ago

5 0

Answer: This is False.

Explanation:

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A police car is at rest parallel to the highway and measures the speed of cars. It sends the signal with a frequency of 1200 Hz,

masha68 [24]

Answer:

a) The car was moving at a speed of $29.167\ m.s^{-1}$

b) The negative sign of $v_o$ denotes that the observer is coming towards the police car which is the source of the sound.

c) $f_o=1283.33\ Hz$

Explanation:

Given:

original frequency of the source, $f=1200\ Hz$

speed of the source, $v_s=0\ m.s^{-1}$

velocity of the obstacle car be, $v_o$

speed of sound, $s=350\ m.s^{-1}$

observed frequency, $f_o=1100\ Hz$

<u>Using the equation from the Doppler's effect:</u>

$\frac{f_o}{f} =\frac{(s+v_o)}{(s-v_s)}$

$\frac{1100}{1200} =\frac{(350+v_o)}{350-0}$

$v_o=-29.167\ m.s^{-1}$

The car was moving at a speed of $29.167\ m.s^{-1}$

The negative sign of $v_o$ denotes that the observer is coming towards the police car which is the source of the sound.

Now when, $v_s=50\ m.s^{-1}$

Then, $f_o=?$

Using the Doppler's eq.:

$\frac{f_o}{1200} =\frac{(350+(-29.167))}{(350-50)}$

$f_o=1283.33\ Hz$

3 0

3 years ago

A 25.0 kg child slides down a long slide in a playground. She starts from rest at a height h1 of 21.00 m. When she is partway do

____ [38]

Answer:

The mechanical energy lost due to friction is 2,424.5 J

Explanation:

Given;

mass of the child, m = 25 kg

intial velocity of the child, u = 0

final velocity of the child, v = 7.8 m/s

initial position of the child, h₁ = 21 m

final position of the child, h₂ = 8 m

Let the energy lost due to heat = ΔE

ΔE + ΔK.E + ΔP.E = 0

ΔE + ¹/₂m(v² - u²) + mg(h₂ - h₁) = 0

ΔE + ¹/₂ x 25(7.8² - 0) + 25 x 9.8(8 - 21) = 0

ΔE + 760.5 J - 3185 J =

ΔE - 2,424.5 J = 0

ΔE = 2,424.5 J

Therefore, the mechanical energy lost due to friction is 2,424.5 J

4 0

3 years ago

which of the following is a chemical change A.ice melting B.ice being carved C.water boiling D.water breaking down into hydrogen

QveST [7]

The chemical change is are to water breaking down into hydrogen and oxygen.

Answer is D.

6 0

4 years ago

Read 2 more answers

Which option is the most accurate description of speed?

puteri [66]

B I think is the answer

5 0

3 years ago

A constant net force of 345 N is applied to slide a heavy stationary

liubo4ka [24]

Answer:

P = 517.5 [kg*m/s]

Explanation:

We must remember that momentum is defined as the product of force by the time of force duration.

$P=F*t$

where:

P = momentum [kg*m/s]

F = force [N]

t = time [s]

$P=345*1.5\\P=517.5[kg*m/s]$

4 0

3 years ago