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3 years ago

SOMEONE PLEASE HELP!!

Physics

1 answer:

Arisa [49]3 years ago

7 0

Hello!

$\large\boxed{\text{C. 7,350,000 J}}$

Use the equation:

$PE = mgh$

Where:

m = mass of the object (kg)

g = acceleration due to gravity (≈9.8 m/s)

h = height above ground (m)

Plug the given values into the equation:

PE = 7500 · 9.8 · 100

PE = 7,350,000 Joules.

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If you swim with the current in a river, your speed is increased by the speed of the water; if you swim against the current, you

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Answer:

11.23%

Explanation:

Lets take

Speed of man in still water =u= 1.73 m/s

Speed of flow of water = v=0.52 m/s

When swims in downward direction then speed of man = u + v

When swims in upward direction then speed of man = u - v

Lets time taken by man when he swims in downward direction is $t_1$ and when he swims in downward direction is $t_2$

Lets distance is d and it will be remain constant in both the case

$d=(u+v)t_1$

$d=(u-v)t_2$

$(1.73+0.52)t_1=(1.73-0.52)t_2$

$t_2=1.85t_1$

Time taken in still water

2 d= t x 1.73

t=1.15 x d sec

$t_1=0.44d\ sec$

$t_2=0.82d\ sec$

total time in current = 0.82 +0.44 d=1.26 d sec

So the percentage time

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Percentage time =11.32%

So it will take 11.32% more time as compare to still current.

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3 years ago

In what layer of earth does the temperature rise the fastest This is for earth science!!!

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Explanation:

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3 years ago

A normal human heart, beating about once per second, creates a maximum 4.00 mV 4.00 mV potential across 0.250 m 0.250 m of a per

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Answer:

1) maximum electric field strength = 0.016 V/m

2)maximum magnetic field strength = 5.33 x 10^(-11) T

3) wavelength = 3 x 10^(8)m

Explanation:

A) We are given;

Frequency (f) = 1 Hz

Maximum Potential ΔV = 4 mV = 4 x 10^(-3) V

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Now, maximum potential formula is given as;

ΔV = E_o•d

Where E_o is maximum electric field strength.

Thus,

E_o= ΔV/d = (4 x 10^(-3))/0.25 = 0.016 V/m

B) The maximum magnetic field strength is given by;

B_o = E_o/c

Where;

c is speed of light = 3 x 10^(8)

B_o is maximum magnetic field strength

Thus,

B_o = 0.016/(3 x 10^(8)) = 5.33 x 10^(-11) T

C) Speed of any electromagnetic wave is given by;

c = fλ

Where;

f is frequency

λ is wavelength

c is speed of light = 3 x 10^(8)

Thus, making λ the subject,

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4 years ago

Air at 20ºC with a convection heat transfer coefficient of 20 W/m2·K blows over a pond. The surface temperature of the pond is 2

dimulka [17.4K]

Answer:

The heat flux between the surface of the pond and the surrounding air is 60 W/ $m^{2}$

Explanation:

Heat flux is the rate at which heat energy moves across a surface, it is the heat transferred per unit area of the surface. This can be calculated using the expression in equation 1;

q = Q/A ...............................1

since we are working with the convectional heat transfer coefficient equation 1 become;

q = h ( $T_{sf} -T_{sd}$ ) ........................2

where q is the heat flux;

Q is the heat energy that will be transferred;

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$T_{sf}$ is the surface temperature = $23^{o}$ C 23°C + 273.15 = 296.15 K;

$T_{sd}$ is the surrounding temperature = $20^{o}$ C = 20°C + 273.15 = 293.15 K;

The values are substituted into equation 2;

q = 20 W/ $m^{2}$ .K ( 296.15 K - 293.15 K)

q = 20 W/ $m^{2}$ .K ( 3 K)

q = 60 W/ $m^{2}$

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4 years ago

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Answer:

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diameter of wire (d) = 0.6 mm = 0.0006 m

radius of wire (r) = 0.0006/2 = 0.0003 m

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Young's modulus = $\frac{stress}{strain}$

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stress = force/area

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stress = $\frac{20}{πx0.0003^{2}}$

stress =70735530.3 N/m^{2}

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strain = 0.5 ÷ 100 = 0.005

therefore Young's modulus = $\frac{stress}{strain}$ = $\frac{70735530.3}{0.005}$ = 1.41 x 10^{10} N/m^{2}

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3 years ago