Gravity obeys the inverse square law. At 6400 km above the center of the Earth (Earth's surface) you weigh x. Twice that reduces your weight to 1/4th. Four times that height reduces your weight to 1/16th. 4 times 6400 km is 25,600 km. But that is above the center of the earth, and the question requests the height above the surface, so we deduct 6400 km to arrive at our final answer: 19,200 km.
Incidentally, it doesn't exactly work the opposite way. At the center of the Earth the mass would be equally distributed around you, and you would therefore be weightless.
Answer:
D a thermometer
Explanation: It measures and track Celcius and Feirinheit.
The answer is B. Weightlessness
Answer:
h = 10 cm
Explanation:
The magnification produced by a mirror is given by :
h' is the image size and h is the object size
We have, h = 10 cm, m = +1
So,
So, the size off the object is same as that of the size of the image i.e. 10 cm.
I think the complete question is:
An old movie poster used a quote "In space, no one can hear you scream!" Which of these best explains the quote?
A) The quote is incorrect, you can hear sound in outer space.
B) Sound cannot be polarized. So, you cannot hear sound in space.
C) Sound is an electromagnetic wave and needs no medium to travel through.
D) Sound needs a medium for the wave to vibrate and there is nothing in space to vibrate.
Answer:
D) Sound needs a medium for the wave to vibrate and there is nothing in space to vibrate.
Explanation:
There are two types of waves:
- Mechanical Waves : These waves requires are medium to travel from one point of space to another point of space. Sound wave is one such example. Since they depend upon medium so speed of travelling also depend upon medium.
- Electromagnetic Waves : These type of waves do not require a medium to travel. If medium exists then it will cause some hindrance in there path but still they will travel. For example: Light waves, X-Rays, Microwaves, Infrared waves, Ultraviolet waves etc.
In space no particle exists so no mechanical waves, such as sound, can travel through it but any electromagnetic wave can travel, such as light. That is why when astronauts are in space walk or when they are in outer space then they do not talk rather they use sign language to communicate
