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2 years ago

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Problem set 3 » (8) river swimming a swimmer heads directly across a river, swimming at her maximum speed of 1.30 m/s relative t

o the water. She arrives at a point 48.0 m downstream from the point directly across the river, 64.0 m wide. What is the speed of the river current?

1 answer:

jasenka [17]2 years ago

5 0

Velocity of swimmer across river = 1.30 m/s

Distance arrived downstream = 48 m

Width of river = 64 m

Time taken to cross river = $\frac{Width of river}{Velocity across river}$

= $\frac{64}{1.30} =49.23 s$

Speed of river current = $\frac{Distance arrived downstream}{Time taken to cross river}$

= $\frac{48}{49.23} = 0.975 m/s$

So, the river is flowing at a speed 0.975 m/s.

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Which statement about homeostasis is true?

Debora [2.8K]

Answer: Homeostasis helps to maintain body equilibrium.

Explanation:

Homeostasis is defined as the maintenance of a fairly constant internal environment in an organism. Body fluids such as blood, lymph, and tissue fluids make up the internal environment of the body, hence by the action of the nervous and endocrine system, there levels are maintained at a body equilibrium, by the help of brain, which has overall control of homeostasis while other parts such as kidney, liver, skin, hormones are also involved.

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2 years ago

An explanation for planetary differentiation is_____________.

Luda [366]

Answer:

C. The process through which distinct layers with characteristic chemical and/or physical properties are formed

Explanation:

I know It cause i took that test last year. Just wanna help GL.

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3 years ago

An observer at the top of a 462-ft cliff measures the angle of depression from the top of the cliff to a point on the ground to

Lana71 [14]

complete question:

An observer at the top of a 462-ft cliff measures the angle of depression from the top of the cliff to a point on the ground to be 5°. What is the distance from the base of the cliff to the point on the ground? Round to the nearest foot

Answer:

a ≈ 5281 ft

Explanation:

The observer at the top of a 462 ft cliff measures the angle of depression from the top of the cliff to a point on the ground to be 5°.

The angle of depression form the top of the cliff = 5°

The 5° is outside the triangle formed . To find the angle in the triangle we have to subtract 5° from 90°. 90° - 5° = 85° Note sum of an angle on a right angle is 90°.

using SOHCAHTOA principle we can solve for the distance from the base of the cliff to the point on the ground(a)

tan 85° = opposite / adjacent

tan 85° = a / 462

cross multiply

462 × tan 85° = a

a = 11.4300523 × 462

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2 years ago

agasfer [191]

Answer:

i/f = i/o + i/i f = focal, o = object, i = image

1 / i = 1 / f - 1 / o = (o - f) / o f

i = o * f / ( o - f) image distance

i = 12.5 * 22 / (12.5 - 22) = -28.9 cm

Image is real

Image is 28.9 cm to left of lens

M = - i / o = = 28.9 / 12.5 = 2.3 magnification (convex lens)

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2 years ago

Suppose a police officer is 1/2 mile south of an intersection, driving north towards the intersection at 40 mph. At the same tim

blagie [28]

Answer:

75.36 mph

Explanation:

The distance between the other car and the intersection is,

$x=x_{0}+V t \\ x=\frac{1}{2}+V t$

The distance between the police car and the intersection is,

$y=y_{0}+V t$

$y=\frac{1}{2}-40 t$

(Negative sign indicates that he is moving towards the intersection)

Therefore the distance between them is given by,

$z^{2}=x^{2}+y^{2}(\text { Using Phythogorous theorem })$

$z^{2}=\left(\frac{1}{2}+V t\right)^{2}+\left(\frac{1}{2}-40 t\right)^{2} \ldots \ldots \ldots(1)$

The rate of change is,

$2 z \frac{d z}{d t}=2\left(\frac{1}{2}+V t\right) V+2\left(\frac{1}{2}-40 t\right)(-40)$

$2 z \frac{d z}{d t}=V+2 V^{2} t-40+3200 t \ldots \ldots \ldots$

Now finding $z$ when $t=0,$ from (1) we have

$z^{2}=\left(\frac{1}{2}+V(0)\right)^{2}+\left(\frac{1}{2}-40(0)\right)^{2}$

$z^{2}=\frac{1}{4}+\frac{1}{4}=\frac{1}{2} \\ z=\sqrt{\frac{1}{2}} \approx 0.7071$

The officer's radar gun indicates 25 mph pointed at the other car then, $\frac{d z}{d t}=25$ when $t=0,$ from

From (2) we get

$2(0.7071)(25)=V+2 V^{2}(0)-40+3200(0)$

$2(0.7071)(25)=V+2 V^{2}(0)-40$

$35.36=V-40$

$V=35.36+40=75.36$

Hence the speed of the car is $75.36 mph$

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3 years ago