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3 years ago

Name one benefit and one limitation of Comparative investigations

2 answers:

8 0

Comparative investigation is a research method that makes comparison across different countries of the world. Limitation : data set in different countries may be defined differently. Benefit : the method is flexible.

tatuchka [14]3 years ago

6 0

Answer: Comparative investigations provide large amounts of information and use a wide range of variables. However, they may reveal relationships that do not always indicate cause and effect.

Explanation:

it was the given answer

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Please help!!!!!!!!!

aleksandr82 [10.1K]

1. This question asks about velocity, so A and B are not correct. The car's velocity after 15 s with acceleration 2.00 m/s² would be

(2.00 m/s²) (15 s) = 30 m/s

[D]

2. Because Ima is slowing down to a stop, the acceleration is negative. Let x be the displacement of her vehicle during this motion. Then

0² - (30.0 m/s)² = 2 (-8.00 m/s²) x

==> x = (30.0 m/s)²/(2 (8.00 m/s²)) = 56.25 m ≈ 65.3 m

[A]

3. Since acceleration is constant, the average velocity is exactly the average of the initial and final velocities:

(21.0 m/s + 0 m/s)/2 = 10.5 m/s

The average (and thus instantaneous) acceleration during this time is equal to the change in velocity divided by the change in time:

(0 m/s - 21.0 m/s)/(6.00 s) = -3.50 m/s²

If x is the distance traveled as the car comes to a stop, then

0² - (21.0 m/s)² = 2 (-3.50 m/s²) x

==> x = (21.0 m/s)² / (2 (3.50 m/s²)) = 63.0 m

[A]

4.a. Assuming the sprinter's acceleration is constant, the average acceleration would be a such that

(11.5 m/s)² - 0² = 2 a (15.0 m)

==> a = (11.5 m/s)² / (2 (15.0 m)) ≈ 4.41 m/s²

4.b. By definition of average acceleration,

4.41 m/s² = (11.5 m/s - 0 m/s)/t

==> t = (11.5 m/s)/(4.41 m/s²) ≈ 2.61 s

5. At maximum height, any thrown object has zero velocity, so if it was thrown with an initial speed v, at its highest point we have

0² - v ² = 2 (-g) (91.5 m)

==> v = √(2g (91.5 m)) ≈ 42.3 m/s

(where I use g = 9.80 m/s²)

6.a. The brick's velocity after 7.0 s is

-g (7.0 s) = -68.6 m/s ≈ -69 m/s

6.b. The brick is presumably dropped from rest, so it is displaced by x such that

(-68.6 m/s)² - 0² = 2 (-g) x

==> x = -240.1 m ≈ -240 m

which is to say it falls a distance of 240 m. (The displacement is negative because we take its initial position to be the origin, and I took the downward direction to be negative.)

3 0

3 years ago

Density is ———- Through the world’s ocean

Montano1993 [528]

Density is varying through the world’s oceans. The density of ocean water is not uniform.

7 0

4 years ago

Miss Piggy is exercising her vocal chords by matching the frequency f = 686 Hz of her speaker 4 m away. Where should Kermit sit

monitta

Answer:

$z=\frac{2n+1}{8}$ for $n=0,1,2,3,...,15$

Where z=0 m is the position of Miss Piggy and z=4 m is the position of the speaker.

Explanation:

Assuming that Miss Piggy emits a sound wave that is in phase with the speaker, and that z=0 is the position of Miss Piggy and z=4 is the position of the speaker, we would have a superposition of two traveling sound waves. Furthermore let's assume that both waves have the same amplitude. The total resulting wave will be given by:

$\psi(t,z)=A\cos(\omega t-kz)+A\cos(\omega t +kz)$ where $\omega$ is the angular frequency of the traveling wave and $k$ is the wave number defined as $k=\frac{2\pi}{\lambda}$ . $\lambda$ is the wavelength of both traveling waves (they have the same wavelength because they have the same frequency). $\lambda=\frac{v}{f}$ where v is the speed of sound.

By using the trigonometric identity $2\cos(A)\cos(B)=\cos(A+B)+\cos(A-B)$ we can rewrite $\psi (t,z)$ as

$\psi (t,z)=2A\cos(\omega t)\cos(kz)$ .

In order for the resulting wave to have maximum destructive interference, that is to be zero for any time t, we need to have

$\cos(kz)=0$

$\implies kz=(2n+1)\cdot \frac{\pi}{2}\implies z=(2n+1)\frac{\pi}{2k}=(2n+1)\frac{\pi}{2}\frac{\lambda}{2\pi}=(2n+1)\cdot \frac{\lambda}{4}$

$\implies z=(2n+1)\cdot\frac{v}{4f}=\frac{2n+1}{8}$

3 0

3 years ago

Chromatic aberration occurs when:___.

worty [1.4K]

Answer:

b. a lens does not focus all colors of light to the same place.

Explanation:

Chromatic aberration is a defect of a lens. In this defect, the lens is unable to focus the different wavelengths of the light on a single focal point. It is also known as chromatic distortion and color fringing. It is caused by the dispersion of light while passing through a lens. As a result, the image might become blurred and different colors are observed around its edges. It can be corrected by the use of a combination of converging and diverging lenses.

Hence, the correct option will be:

b. a lens does not focus all colors of light to the same place.

4 0

3 years ago

Braking distance is the distance a car travels from the time a person applies the brakes to when the car comes to a complete sto

Dvinal [7]

The kinetic energy of an object increases as its velocity increases. Moreover, we see that the braking distance of the car increases as its velocity increases. Therefore, the breaking distance increases when the kinetic energy of the car is higher. This is evident in the graph where when the velocity is lower, the kinetic energy is lower and the braking distance is less.

6 0

4 years ago