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3 years ago

Answer all of these questions and you will get the brainlist

Physics

2 answers:

adelina 88 [10]3 years ago

6 0

Answer:

1. kinetic energy = ½mv²

m= 2.1 kg

v = 30m/s

Ek = ½ ×2.1×30×30

= 945J

2. potential energy = mgh

m = 190kg

g = 9.8

h = 45m

Ep = 190×9.8 × 45

= 83790J

3.potential energy = mgh

m= 75kg

g= 9.8

h = 300m

Ep = 75×9.8×300

= 220,500J

Gnoma [55]3 years ago

5 0

Answer:

2 ans : the bell has 8550 J energy

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The speed of light in a vacuum is 2.99x10^8 m/s. calculate its speed in miles per hour.

34kurt

You'll never get the correct answer without the correct conversion factor. Note carefully that you have no decimal. It should be
<span>1 km = 0.6214 miles </span>
<span>1000 m = 1 km </span>
<span>60 seconds = 1 minute </span>
<span>60 minutes = 1 hour. </span>
<span>2.998E8 m/s x (1 km/1000m) x (0.6214 miles/km) x (60 sec/min) x (60 min/hr) = ?</span>

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3 years ago

At a rock concert, the sound intensity 1.0 m in front of the bank of loudspeakers is 0.10 W/m². A fan is 30 m from the loudspeak

Klio2033 [76]

To solve this problem we will apply the concepts related to the Area, the power and the proportionality relationships between intensity and distance.

The expression for sound power is,

$P = AI$

Here,

A = Area

I = Intensity

P = Power

At the same time the area can be written as,

$A = \frac{\pi d^2}{4}$

Now the intensity is inversely proportional to the square of the distance from the source, then

$I \propto \frac{1}{r^2}$

The expression for the intensity at different distance is

$\frac{I_1}{I_2}= \frac{r^2_2}{r_1^2}$

Here,

$I_1$ = Intensity at distance 1

$I_2$ = Intensity at distance 2

$r_1$ = Distance 1 from light source

$r_2$ = Distance 2 from the light source

If we rearrange the expression to find the intensity at second position we have,

$I_2 = I_1 (\frac{r_1^2}{r_2^2})$

If we replace with our values at this equation we have,

$I_2 = (0.10W/m^2)(\frac{1.0m^2}{30.0m^2})$

$I_2 = 1.11*10^{-4} W/m^2$

Now using the equation to find the area we have that

$A = \frac{\pi (8.4*10^{-3}m)^2}{4}$

$A = 5.5*10^{-5}m^2$

Finally with the intensity and the area we can find the sound power, which is

$P = AI$

$P = (5.5*10^{-5}m^2)(1.11*10^{-4}W/m^2)$

$P = 6.1*10^{-9}J/s$

Power is defined as the quantity of Energy per second, then

$E = 6.1*10^{-9}J$

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3 years ago

What were Rosalind Franklin, James Watson, and Francis Crick’s discovery, and what did it lead to? In three to five sentences, e

Vanyuwa [196]

Rosalind Franklin, James Watson, and Francis Crick’s discovered the DNA's Double Helix.

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In 1953, James Watson and Francis Crick's used other scientists' work to create a model of DNA in that they used Rosalind Franklin's photo to help them determine that deoxyribonucleic acid (DNA) was a double helix.

Furthermore, the discovery of DNA's Double Helix by Rosalind Franklin, James Watson, and Francis Crick led to modern molecular biology, which has helped many scientists and researcher to understand how genes control the chemical processes in the body of a living organism.

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1 year ago

A boy is trying to roll a bowling ball up a hill, as shown in the image below. If

kherson [118]

The minimum initial velocity that the ball must have for it to reach the top of the hill is 21 m/s. The correct option is D.

<h3>What is mechanical energy?</h3>

The mechanical energy is the sum of kinetic energy and the potential energy of an object at any instant of time.

M.E = KE +PE

A boy is trying to roll a bowling ball up a hill. The friction is ignored. The ball must have to reach the top of the hill with a velocity. The acceleration due to gravity, g = 9.8 m/s²

The conservation of energy principle states that total mechanical energy remains conserved in all situations where there is no external force acting on the system.

M.E bottom of hill = M.E on top of hill

Kinetic energy + Potential energy = Kinetic energy + Potential energy

1/2 mu² + 0 = 0 + mgh

At the top of hill, the velocity will become zero. So, final kinetic energy is zero.

Substituting the values, we have

1/2 x u² = 9.8 x 22.5

u = sqrt [2 x9.8 x 22.5 ]

u= 21 m/s

Thus, the minimum initial velocity that the ball must have for it to reach the top of the hill is 21 m/s.

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2 years ago

You are an electrician installing the wiring in a new home. The homeowner desires that a ceiling fan with light kits be installe

In-s [12.5K]

Answer:

3 fans per 15 A circuit

Explanation:

From the question and the data given, the light load let fan would have been

(60 * 4)/120 = 240/120 = 2 A.

Next, we add the current of the fan motor to it, so,

2 A + 1.8 A = 3.8 A.

Since the devices are continuos duty and the circuit current must be limited to 80%, then the Breaker load max would be

0.8 * 15 A = 12 A.

Now, we can get the number if fans, which will be

12 A/ 3.8 A = 3.16 fans, or approximately, 3 fans per 15 A circuit.

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3 years ago