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Alekssandra [29.7K]

2 years ago

11

A current of 9 A flows through an electric device with a resistance of 43 Ω. What must be the applied voltage in this particular

circuit?
A. 4.8 V
B. 4.8 A
C. 387 V
D. 387 A

1 answer:

blondinia [14]2 years ago

6 0

The answer is D. Hope this helps you!

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3 years ago

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An object 5.Ocm in the length is placed at a distance of 20cm in front of convex mirror

andrew-mc [135]

Answer:

Position = $\frac{60}{7}\ cm$ behind the mirror

Nature = Virtual and Erect

Size = $\frac{15}{7}\ cm$ : Diminished

Explanation:

Sign convention-Distance measured to the left of pole is negative and to the right of pole is positive.

Object distance = u = -20 cm

Focal length = f = Radius of curvature/2 = 30/2 = 15 cm

We have to use mirror formula to find image distance.

$\frac{1}{u}+\frac{1}{v}=\frac{1}{f}\\ \frac{1}{-20}+\frac{1}{v}=\frac{1}{15}\\ \frac{1}{v}=\frac{7}{60}\\v=\frac{60}{7}\ cm$

Since the image distance is positive, it is formed behind the mirror or a virtual image is formed.

Magnification = $=\frac{h_{image}}{h_{object}}=$ $-\frac{v}{u}=\frac{60}{7\times20}=\frac{3}{7}$

Height of the object = 5 cm

Height of the image = $5\times\frac{3}{7}=\frac{15}{7}\ cm$

Since the height of the image is positive and less than the size of object,it is erect and diminished.

4 0

3 years ago

What will be the restoring force if a spring with a spring constant of 45 newtons per meter is pulled 0.03 meters in the downwar

allsm [11]

To calculate for the force in a spring, we use Hooke's Law which relates force and the displacement of the spring. It is said that the force is directly proportional to the displacement. So, it will have the equation F = kx where k is a constant and it is the spring constant.

F = kx
F = 45 N/m (0.03)
F = 1.35 N

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2 years ago

A 280-m-wide river flows due east at a uniform speed of 4.7m/s. A boat with a speed of 7.1m/s relative to the water leaves the s

tamaranim1 [39]

Answer:

(a) The speed is 7.96 m/s

(b) The direction is 76 degree from positive X axis in counter clockwise direction.

Explanation:

Width of river = 280 m

speed of river, vR = 4.7 m/s towards east

speed of boat with respect to water, v(B,R) = 7.1 m/s at 26 degree west of north

$vR = 4.7 i \\\\v(B,R) = 7.1 (- sin 26 i + cos 26 j) = - 3.1 i + 6.4 j$

(a) The velocity of boat with respect to ground is

$\overrightarrow{v}_{(B,R)}=\overrightarrow{v}_{(B,G)}-\overrightarrow{v}_{(R,G)}\\\\- 3.1 \widehat{i} +6.4 \widehat{j}=\overrightarrow{v}_{(B,G)} - 4.7 \widehat{i}\\\\\overrightarrow{v}_{(B,G)} = 1.6 \widehat{i} + 6.4 \widehat{j}\\\\{v}_{(B,G)} = \sqrt{1.6^2 + 6.4^2}=6.96 m/s$

(b) The direction is given by

$tan\theta = \frac{6.4}{1.6} =4\\\\\theta = 76^o$

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2 years ago

What is the best definition for hypothermia? Damage to skin caused by long exposure to freezing temperatures Very low internal b

Murljashka [212]

Answer:

Advertisement. When your body temperature drops, your heart, nervous system and other organs can't work normally. Left untreated, hypothermia can lead to complete failure of your heart and respiratory system and eventually to death. Hypothermia is often caused by exposure to cold weather or immersion in cold water.

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2 years ago