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3 years ago

How many birds have tested positive for West Nile virus?

1 answer:

5 0

I believe the last time the dead bird count was updated (12/16/16), there is a count of 1,350 dead birds. There is 1,350 dead birds from 33 countries have tested positive for WNV in 2016.

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A 20.0 cm tall object is placed 50.0 cm in front of a convex mirror with a radius of curvature of 34.0 cm. Where will the image

Neko [114]

Answer:

1.Theimage will be located at -0.13m or -13 cm

2.The height of the image will be 0.052m or 5.2cm

Explanation:

Given that;

Height of object, h=20 cm = 0.2m

Object distance in front of convex mirror, o,= 50 cm =0.5m

Radius of curvature, r, =34 cm =0.34m

Let;

Image distance, i,=?

Image height, h'=?

You know that focal length,f, is half the radius of curvature,hence

f=r/2 = 0.34/2 = 0.17m ( this length is inside the mirror, in a virtual side, thus its is negative)

f= -0.17m

Apply the relationship that involves the focal length;

$=\frac{1}{o} +\frac{1}{i} =\frac{1}{f}$

$=\frac{1}{0.5} +\frac{1}{i} =-\frac{1}{0.17}$

Re-arrange to get i

$\frac{1}{i} =-2-5.88\\\\\\\frac{1}{i} =-7.88\\\\i=-0.13m$

This is a virtual image formed at a negative distance produced through extension of drawing rays behind the mirror if you use rays to locate the image behind the mirror

Apply the magnification formula

magnification, m=height of image÷height of object

$m=\frac{h'}{h} =-\frac{i}{o}$

substitute the values to get the height of image h'

$\frac{h'}{0.20} =-\frac{-0.13}{0.5} \\\\\\h'=\frac{0.13*0.20}{0.5} \\\\\\h'=\frac{0.025}{0.5} =0.052m\\\\\\h'=5.2cm$

5 0

3 years ago

If this resolving power is diffraction-limited, to what effective diameter of your eye's optical system does this correspond? us

ZanzabumX [31]

"This resolving power" was obviously stated earlier, somewhere before the point where you started copying. With no resolving power specified, there's actually no question, and so no answer.

5 0

3 years ago

A man climbs a wall that has a height of 8.4 meters and gave the potential energy of 4620 joules. His mass is about_____ kilogra

Dmitrij [34]

Gravitational potential energy = mass x acceleration due to gravity x height
GPE=mgh
4620=mx9.81x8.4
4620/(9.81x8.4)=m=56.1 kg

7 0

2 years ago

Two bodies are falling with negligible air resistance, side by side, above a horizontal plane. If one of the bodies is given an

borishaifa [10]

Answer:a

Explanation:

Given

two bodies are falling with negligible air Resistance and one of the body is given a slight horizontal acceleration

since there is no change in vertical acceleration therefore time taken by both bodies is same irrespective of change in horizontal direction

suppose both start from rest from a height of h

time taken

$t=\sqrt{\frac{2h}{g}}$

The only difference is that body with horizontal acceleration will be some distance away from first

4 0

3 years ago

Read 2 more answers

[Assume g = 10m/s?] If a girl is running along a straight road with a uniform velocity 1.5 m/s, find her acceleration. (Ans: 0)

DerKrebs [107]

Answer:

Her acceleration is 0 m/s²

Explanation:

We note that the motion of the girl is on a straight road, therefore;

The vertical acceleration (e.g. due to gravity, <em>g)</em> on the horizontal motion = 0

The horizontal acceleration, a = (Change in velocity, Δv)/(Change in time, Δt)

For uniform velocity, the change in velocity, Δv = 0

Therefore, fore any change in time, Δt, we have;

a = Δv/Δt

Her acceleration, a = 0/Δt = 0

Her acceleration, a = 0 m/s²

7 0

2 years ago