Microscope lenses , glasses for people who can't see faraway as well and microwave lenses which reflect electromagnetic radiation. Oh and curved mirrors.
Answer:
Speed of wind = 50mi/hr, Speed of plane in still air = 400mi/hr
Explanation:
Let the speed of the wind = Vw,
Speed of the plane in still air = Vsa,
The first trip the average speed of the plane = 1575mi/4.5hours = 350mi/hr
The coming trip the wind behind = 1575mi/3.5hrs = 450
Write the motion in equation form
First trip ( the plane flew into the wind)
Vaverage = Vsa - Vw
350 = Vsa - Vw
Second trip the wind was behind
450 = Vsa +Vw
Adding the two equation
800 = 2Vas
Vas = 800/2 = 400mi/hr
Substitute for Vas into equation 1
350mi/hr = 400mi/hr - Vw
Vw = 400-350 = 50mi/hr
Answer:
Explanation:
The frequency of a sodium vapor lamp, 
We need to find the wavelength of light. The relation between wavelength, frequency and speed of light is given by :
So, the wavelength of light is equal to 
.
Answer:
Hearing range describes the range of frequencies that can be heard by humans or other animals, though it can also refer to the range of levels. The human range is commonly given as 20 to 20,000 Hz, although there is considerable variation between individuals, especially at high frequencies, and a gradual loss of sensitivity to higher frequencies with age is considered normal. Sensitivity also varies with frequency, as shown by equal-loudness contours. Routine investigation for hearing loss usually involves an audiogram which shows threshold levels relative to a normal.
Several animal species are able to hear frequencies well beyond the human hearing range. Some dolphins and bats, for example, can hear frequencies up to 100,000 Hz. Elephants can hear sounds at 14–16 Hz, while some whales can hear infrasonic sounds as low as 7 Hz (in water).
Explanation:
HOPE THIS HELPS!!!
(150 km/hr) x (1000 m/km) x (hr/3600sec) = 41-2/3 m/sec
Acceleration = (change in speed) / (time for the change)
Change in speed = (41-2/3 minus 0) = 41-2/3 m/s
Time for the change = 0.5sec.
Acceleration = (41-2/3 m/s) / (0.5 sec) = 83-1/3 m/s² .
Acceleration of gravity = 9.8 m/s² .
Acceleration of sneezed air = (83-1/3) / (9.8) = <em>8.5 g </em>(rounded)
