Objectives Pecina
y
01:Posttest 01:Motion Along a Straight Line
eration
1. An elevator moving down passes its neighbor, an elevator moving up. Their speed relative to one another is 8 m/s. What is the velocity of each
elevator relative to someone standing on the first floor? Assume that the elevators are traveling at the same speed, and that the upward direction is
positive.
tant Acceleration
O Both elevators are moving at 8 m/s.
y Falling Objects
O One elevator is moving at 4 m/s; the other elevator is moving at -4 m/s.
O Both elevators are moving at 4 m/s.
tive Velocity
O One elevator is moving at 8 m/s; the other elevator is moving at -8 m/s.
Posttest
on in a Plane
ton's Laws of Motion
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blications of Newton's
Description
440
11:53 PM
4/4/2021

B

Explanation:

Given that an elevator moving down passes its neighbor, an elevator moving up. Their speed relative to one another is 8 m/s. What is the velocity of each elevator relative to someone standing on the first floor? Assume that the elevators are traveling at the same speed, and that the upward direction is

positive.

Solution

Given that upward direction is positive, then, the downward direction will be negative.

To get a relative velocity of 8m/s

4 - ( - 4 ) = 8

Therefore, the correct answer will be

One elevator is moving at 4 m/s; the other elevator is moving at -4 m/s

Which is option B

Because the negative multiply by negative sign will give positive sign.

Given

4 + 4 = 8.

laticia draws the diagram below to show earth’s magnetic field.

answer

the arrows to the right of earth should point up.

scattering of light by tiny particles in air to produce the colors we see on sky, is dependent on the following factors:

(i) wavelength of light

(ii) size of the scattering particle  

(iii) distance traveled by light through the atmosphere.

according to rayleigh's law of scattering, the amount of scattering is inversely proportional to the fourth power of its wavelength. shorter the wavelength, greater is its scattering. hence violet/blue light is scattered more than red.

sun's light is a composite light ( visible light) with wavelengths in the range 400 nm (violet) to 700 nm (red). as sunlight passes through our atmosphere, the molecules of air scatter light according to their wavelengths. during sunrise and sunset, the sun's position is below the horizon. hence light from the sun travels a greater distance in the atmosphere when compared to its position a noon.

as sunlight enters the earth's atmosphere, blue light is scattered away and at the end of its journey in the sky, only red and orange wavelengths remain in the beam.

hence at sunrise and sunset, the sky appears reddish orange.