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3 years ago

As a projectile moves down its vertical velocity is positive?

1 answer:

7 0

When YOU start working on a problem, if the question doesn't TELL you which direction is positive and which is negative, then YOU get to decide before you start solving the problem.

MOST often, people use positive for UP and negative for DOWN, just because that's the way we naturally think of 'up' and 'down'. But there's no law. If you want to, you can just as well call up 'negative' and call down 'positive'.

You might be interested in

It is observed that the number of asteroids (or meteoroids) of a given diameter is roughly inversely proportional to the square

MaRussiya [10]

Answer:

(a) M = =1.57 *10²¹kg

(b) M = =1.57 *10²⁰kg

(d) M = =1.57 *10¹⁸kg

Explanation:

(a) For 1000km body, diameter D = 1000km = 1,000,000 m

and N = (1000/D)² = (1000/1000km)² = 1

substituting into the formula, we have

M = 1 * 4/3 π*3000*[1000000/2]³

=1.57 *10²¹kg

(b) For 100km body, diameter D = 100km = 100,000 m

and N = (1000/D)² = (1000/100km)² = 100

substituting into the formula, we have

M = 1 * 4/3 π*3000*[100000/2]³

=1.57 *10²⁰kg

and N = (1000/D)² = (1000/10km)² = 100

substituting into the formula, we have

M = 1 * 4/3 π*3000*[10000/2]³

=1.57 *10¹⁹kg

and N = (1000/D)² = (1000/1km)² = 100

substituting into the formula, we have

M = 1 * 4/3 π*3000*[1000/2]³

=1.57 *10¹⁸kg

4 0

3 years ago

What causes the random, zig-zag movement (Brownian motion) of smoke particles suspended in air?

lidiya [134]

Answer:

It is caused by air molecules colliding with smoke particles

Explanation:

To start with, Brownian motion is the erratic or irregular movement of very small particles in a medium due to continuous bombardment by molecules that surround the medium.

Thus, smoke moves in a Zig-Zag manner (Brownian motion) due to continious air bombardment. If it were pollen grain suspended in water, the erratic movement (Brownian motion) of the grains is caused by bombardment from water molecules.

8 0

3 years ago

A gate at the bottom of a dam is 10 ft tall by 30 ft wide. The specific weight of the water is 62.4 lbf/ft3. If the water is 50

Burka [1]

Answer:

The total force is most nearly 940,000lbf

Explanation:

Total force = specific weight × volume

Volume = length × width × depth = 10ft × 30ft × 50ft = 15,000ft^3

Total force = 62.4lbf/ft^3 × 15,000ft^3 = 936,000lbf which is most nearly 940,000lbf

4 0

3 years ago

Which situations might cause two observers (A and B) to measure different frequencies for the same vibrating object? Select the

Alex787 [66]

We want to explain why two different observes may measure different frequencies for the same vibrating object.

We will see that the two correct options are:

Observer A is stationary and Observer B is moving.
Observer A and Observer B are moving at different speeds relative to each other.

Let's assume that the vibrating object is a guitar string. Thus, the string makes a noise, and from that noise, we can estimate the frequency at which the string vibrates.

Now there appears a really cool effect, called the Doppler Effect. It says that the apparent change of frequency is due to the motion of the observer or the source of the frequency (or both).

For example, if you move towards the vibrating string, the perceived frequency will be larger, and you will hear a "higher" sound.

While if you move away from the string, the opposite happens, and you will hear a "lower" sound.

Then the only thing that impacts in how we perceive the frequency is our velocity relative to the source.

So, why do observers A and B measure different frequencies?

The two correct answers are:

Observer A is stationary and Observer B is moving.
Observer A and Observer B are moving at different speeds relative to each other.

If you want to learn more, you can read:

brainly.com/question/17107808

6 0

3 years ago

Three noise sources produce volume (loudness) levels of 70, 73, and 80 dB when acting separately. When the sources act together,

Mashutka [201]

Sound at 70 dB is 70 dB louder than the human reference level. That's 10⁷ times as much as the reference sound power.

Sound at 73 dB is 73 dB louder than the human reference level. That's 10⁷.³ or 2 x 10⁷ times as much as the reference sound power.

Sound at 80 dB is 80 dB louder than the human reference level. That's 10⁸ or 10 x 10⁷ times as much as the reference sound power.

Now we can adumup:

Intensity of all 3 sources = (10⁷) + (2 x 10⁷) + (10 x 10⁷)

Intensity = (13 x 10⁷) times the sound power reference intensity.

Intensity in dB = 10 log (13 x 10⁷) = 10 (7 + log(13)

Intensity = 70 + 10 log(13)

Intensity = 70 + 10 (1.114)

Intensity = 70 + 11.14

Intensity = 81.14 dB

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Looking at the questioner's profile, I seriously wonder whether I'll ever get a comment in return from this creature, and how I'll ever find out if my solution is correct. For that matter, I'm also seriously questioning how and whether my solution will ever be used for anything.

8 0

3 years ago