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Georgia [21]
3 years ago
11

a cell supplies a current 0.9A through a resistance of 2 ohms and a current of 0.3A through a resistance of 7 ohms. what is inte

rnal resistance
Physics
1 answer:
umka2103 [35]3 years ago
8 0

We model the cell's internal resistance as an additional resistor in the circuit. We will use V = IR to calculate the voltage drops over each resistor for both circuits.

Circuit 1: 0.9A current, internal resistance r, resistor 2Ω

V = 0.9r + 0.9(2) = 0.9r + 1.8

Circuit 2: 0.3A current, internal resistance r, resistor 7Ω

V = 0.3r + 0.3(7) = 0.3r + 2.1

Since V should be the same for both circuits, set the total voltage drops equal to each other and solve for r:

0.9r +1.8 = 0.3r + 2.1

0.6r = 0.3

r = 0.5Ω

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Sergio [31]

see

below

Explanation:

refractive index = speed of light in vacuum / speed of light in medium

light travels at a speed of 3.0 x 10^8 m/s in vacuum

refractive index = 3.0 x 10^8 / 2.0 x 10^8

refractive index = 1.5

hope this helps, please mark it

4 0
3 years ago
A boy swings a ball on a string at constant speed in a circle that has a circumference equal to 6 m. What is the work done on th
Grace [21]

Answer:

0 J

Explanation:

From the diagram below; we would notice that the Force (F) = Tension (T)

Also the angle θ adjacent to the perpendicular line = 90 °

The Workdone W = F. d

W = Fd cos θ

W = Fd cos 90°

W = Fd (0)

W = 0 J

Hence the force is perpendicular to the direction of displacement and the net work done in a circular motion in one complete revolution is = 0

8 0
3 years ago
What’s the difference between expressed/implied powers, concurrent powers, and reserved powers?.
Lisa [10]

Answer:

A reserved power is a power specifically reserved to the states. Powers include setting up local governments and determining the speed limit. A concurrent power is a power that is given to both the states and the federal government.

Explanation:

3 0
3 years ago
The Apollo Lunar Module was used to make the transition from the spacecraft to the moon's surface and back. Consider a similar m
lions [1.4K]

Answer:

Explanation:

a. Landing height is

H=1.3m

Velocity of lander relative to the earth is, i.e this is the initial velocity of the spacecraft

u=1.3m/s

Velocity of lander at impact, i.e final velocity is needed

v=?

The acceleration due to gravity is 0.4 times that of the one on earth,

Then, g on earth is approximately 9.81m/s²

Then, g on Mars is

g=0.4×9.81=3.924m/s²

Then using equation of motion for a free fall body

v²=u²+2gH

v²=1.3²+2×3.924×1.3

v²=1.69+10.2024

v²=11.8924

v=√11.8924

v=3.45m/s

The impact velocity of the spacecraft is 3.45m/s

b. For a lunar module, the safe velocity landing is 3m/s

v=3m/s.

Given that the initial velocity is 1.2m/s²

We already know acceleration due to gravity on Mars is g=3.924m/s²

The we need to know the maximum height to have a safe velocity of 3m/s

Then using equation of motion

v²=u²+2gH

3²=1.2²+2×3.924H

9=1.44+7.848H

9-1.44=7.848H

7.56=7.848H

H=7.56/7.848

H=0.963m

The the maximum safe landing height to obtain a final landing velocity of 3m/s is 0.963m

8 0
3 years ago
In a parachute, falling steadily at 7.5m/s, how long does it take to reach the ground from 3,000 m high?
photoshop1234 [79]

Answer:

25 minutes

Explanation:

4 0
3 years ago
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