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MArishka [77]
3 years ago
7

device for heating a cup of water in a car connects to the car's battery, which has an emf E = 10.0 V and an internal resistance

rint = 0.07 Ω . The heating element that is immersed in the cup of water is a resistive coil with resistance R.
Physics
1 answer:
tatuchka [14]3 years ago
6 0

Answer:

R = 0.93 ohms

Explanation:

Let's start by calculating the resistance of the coil,

V = I ( R + r )

Make R the subject of the above equation.

Hence,

V = IR + Ir

V - Ir = IR

( V - Ir )/I = R

Given that V = 10V

r = 0.07ohms

I = 10A ( this is an assumption )

( 10 - 10×0.07 ) ÷ 10

R = 0.93 ohms

Note: r is the internal resistance, R is the resistance, I is the current and the emf is represented as V. Since current was supposed to be included in the question but it was not, hence it was assumed to be 10A . Meaning whatsoever value is given for current will be substituted into the equation. Thanks

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A helicopter starting on the ground is rising directly into the air at a rate of 25 ft/s. You are running on the ground starting
rusak2 [61]

Answer:

The rate of change of the distance between the helicopter and yourself (in ft/s) after 5 s is \sqrt{725} ft/ sec

Explanation:

Given:

h(t) =  25 ft/sec

x(t) = 10 ft/ sec

h(5) = 25 ft/sec . 5 = 125 ft

x(5) = 10 ft/sec . 5 = 50 ft

Now we can calculate the distance between the person and the helicopter by using the Pythagorean theorem

D(t) = \sqrt{h^2 + x^2}

Lets find the derivative of distance with respect to time

\frac{dD}{dt} (t)  = \frac{2h \cdot \frac{dh}{dt} +2x \cdot\frac{dx}{dt}} {2\sqrt{h^2 + x^2}}

Substituting the values of h(t) and  x(t) and simplifying we get,

\frac{dD}{dt}(t) = \frac{50t \cdot \frac{dh}{dt} + 20 \cdot \frac{dx}dt}{2\sqrt{625\cdot t^2 + 100 \cdot t^2}}

\frac{dh}{dt} = 25ft/sec

\frac{dx}{dt} = 10 ft/sec

\frac{Dd}{dt} (t) = \frac{1250t +200t}{2\sqrt{725}t}  = \frac{725}{\sqrt{725}}  = \sqrt{725} ft / sec

5 0
3 years ago
An airplane has a starting velocity of 300m/s. It then accelerates at a rate of 45m/s2 for a time of 10s. What is it's final vel
Olenka [21]
A = (v - u) / t

a = acceleration
v = final velocity
u = initial velocity
t = time

45 = (v - 300) / 10

45 × 10 = v - 300

450 + 300 = v

v = 750 m/s

Hope this helps!

P.S. Let me know if you need an explanation
8 0
2 years ago
A long straight cylindrical shell has an inner radius R_i and an outer radius R_0. It carries a current i, uniformly distributed
Irina-Kira [14]

Answer:

Correct answer is option D

- Wire is on the cylinder axis and carries current i in the direction opposite to that of the current in the shell

Explanation:

- It cannot be Option E, because the magnetic field outside the wire would not be 0 due to the current carried by the conductor

-Also, the parallel wire cannot carry current in the same direction because, that would amplify the magnetic field created by the outer cylinder (since B is dir. proportional to the current) -and now, that leaves only option C and D. If, it is Option C, then that means one side of the cylinder would be more closer to the parallel wire than the other, so there would be different B fields on the two opposite sides of the cylinder. So, that means the answer is option D.

7 0
3 years ago
The rate traveled from Amarillo to Austin by a bus averages 60 miles per hour. The bus arrived in Austin after eight hours of tr
jeyben [28]

Answer:

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Explanation:

bus average from amarllo to austin = 60 miles per hour

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from the information given in the question:

60 mph ---    8 h

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By using The inverse variation:

60 : 48 = x : 8

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x = 480/48

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the car would arrive after 10 hr to Austin.

3 0
3 years ago
If an electron is accelerated from rest through a potential difference of 1200V find its approximate velocity at the end of this
kolbaska11 [484]

Answer: 2.1 × 10^7 m/s

Explanation:

Please see the attachments below

8 0
3 years ago
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