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3 years ago

Two vectors A and B are such that A =1,B=2,A.B=1 find angle

Physics

1 answer:

romanna [79]3 years ago

7 0

Answer: $60^{\circ}$

Explanation:

Given

$\mid\Vec{A}\mid=1$

$\mid\Vec{B}\mid=2$

And $A\cdot B=1$

We know $\vec{A}\cdot \vec{B}=\mid\Vec{A}\mid\mid\Vec{B}\mid\cos \theta$

Where $\theta$ is the angle between them

Substituting the values

$1=1\times 2\cos \theta$

$\cos \theta =\dfrac{1}{2}$

$\theta =60^{\circ}$

Thus the angle between $A$ and $B$ is $60^{\circ}$

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400 gallons of pesticide is accidentally spilled into a lake and uniformly mixes with the water. The volume of the lake includin

svet-max [94.6K]

Answer:

t=27725.8minutes

Explanation:

To determinate use the law the change of volume in determinate time is derivate so:

$\frac{dV}{dt}=flowin-flowout$

The flow in is zero and the flow out is modeling with V as the volume out in the volume of the lake in the reason of change.

$\frac{dV}{dt}=0-(\frac{V}{10x10^{8}})*5000\\\frac{dV}{dt}=-5x10^{-5}*V \\dV*V=-5x10^{-5}*dt$

Integrate to get the volume function

$\int\limits{\frac{1}{V}}\, dv=\int\limits{-5x10^{-5} }\, dt\\ ln(V)=-5x10^{-5}*t\\ln*e(V)=C*e^{-5x10^{-5}*t}\\$

The find the constant C in the time t=0 the volume is knowing so:

$t=0s\\V=400\\V=C*e^{0}\\C=400$

$V=400*e^{-5x10^{-5}*t}$

The volume is 1 part per million so:

$\frac{V}{10x^{8}}=\frac{1}{10x^{6}}\\ V=100$

$V=400*e^{-5x10^{-5}*t}\\100=400*e^{-5x10^{-5}*t}\\\frac{100}{400}=e^{-5x10^{-5}*t}\\ln*\frac{1}{4}=ln*e^{-5x10^{-5}*t}\\-ln(4)=-5x10^{-5}*t\\ t=\frac{-ln(4)}{-5x10^{-5}}=27725.88\\t=27725.8minutes$

8 0

3 years ago

Which describes how the same force affects a small mass and a large mass

n200080 [17]

The same force accelerates a small mass faster than
it accelerates a large mass.

It's easier to get a little red wagon going by pushing it
than it is to get a school bus going by pushing it.

6 0

3 years ago

Imagine our Solar System is moving in the Milky Way towards a group of two stars. Star A is a Red star that is slightly closer t

Juliette [100K]

Answer:

None of the stars give of light that is red-shifted

Explanation:

Motion of the observer or the source will cause a change in the wavelength of a wave. This is known as the Doppler effect. When an object and observer are getting close, blue shift occurs i.e., the wavelength gets shorter. When an object and observer are getting farther red shift occurs i.e., the wavelength gets longer.

Here, both the stars are getting closer to us so blue shift will occur.

6 0

3 years ago

The closely packed cones in the fovea of the eye have a diameter of about 2 Î¼m. For the eye to discern two images on the fovea

Marina CMI [18]

Answer:

The distance between the object is $l=0.0056\ cm$

Explanation:

The free body diagram of this setup is on the first uploaded image

From the question

The diameter of closely packed cones in the fovea of the eye is = $2 \mu m$

The distance of separation by one cone(not excited ) is $d = 4\mu m = 4*10^{-4}cm$

The distance between the two point-like object is l

The diameter of the eye is D = 2 cm

The distance of the two point-like object from the near point of the eye is A = 28 cm

From the diagram we see that the light from the two point-like object form a triangle of similar base l and d and height D and A

So for a triangle with similar base we have that

$\frac{l}{A} =\frac{d}{D}$

$\frac{l}{28} = \frac{4*10^{-4}}{2}$

making l the subject we have

$l = \frac{28 *4*10^{-4}}{2}$

$l=0.0056\ cm$

5 0

3 years ago

Read 2 more answers

Electromagnetic waves are transverse waves. They consist of traveling electric and magnetic fields which oscillate periodically.

masha68 [24]

Answer:

The answer is D.) 90

Explanation:

the electromagnetic wave is a transverse wave. the electric field makes an angle of 90° with the magnetic field. both these fields, in turn, make an angle of 90° with the direction of movement of the wave.

7 0

3 years ago