Presently, the speed of light in a vacuum is defined to be exactly 299,792,458 m/s (approximately 186,282 miles per second). . An early experiment to measure the speed of light was conducted by Ole Romer, a Danish physicist, in 1676. Using a telescope, Ole observed the motions of Jupiter and one of its moons, Io
In physics, gravity is the natural force that causes things to fall toward the earth. The noun gravity can also mean seriousness or solemnity. Someone who conducts themselves with an air of gravity is someone who takes what they are doing seriously.
Answer:
Explanation:
Given:
- original frequency of sound wave,
- speed of the sound source,
- original speed of sound wave from the source,
<u>According to the Doppler's effect:</u>
The sound is reflected from the wall and the source is moving towards the wall and observer is also riding the same source.
The velocity of the observer, 
Answer: Hydrogen and Helium > Hydrogen compounds > Rocks > Metals
Explanation: The solar nebular system contains 98% Light Gases of both Hydrogen and Helium (produced in the Big Bang); followed by 1.4% of Hydrogen Compounds including water, methane, and ammonia; then followed by 0.4% of Rocks like Silicates; and lastly 0.2% of Metals including Iron, Nickel and Aluminium.
A.cooler and hotter rock rise but do not sink.
B.hotter and cooler rock sink but do not rise.
C.hotter rock rises and cooler rock sinks.
D.cooler rock rises and hotter rock sinks.
hotter rock rises and cooler rock sinks.
Answer: Option C.
<u>Explanation:</u>
The process that happens inside the surface of earth makes the rocks inside the surface to either expand or shrink in size because of the presence of heat inside the surface.
Heat rises and as the warmer rock gets further away from the super heated center of the Earth it begins to cool off and starts to sink back toward the super heated center of the Earth where it is reheated and the whole process starts over again. That is what a convection current is.
