Answer: Larmor suggested in 1919 that a self-exciting dynamo could explain the magnetic field of the earth, as well as that of the sun and other stars, but it was Elsasser and Bullard in the 1940s who showed how motion in the liquid core of the earth might produce a self-sustaining magnetic field. By this time seismology and other studies had given a clearer picture of the earth, as having a solid inner core, a liquid outer core, both with a composition more of metal (mainly iron) than rock, and a rocky mantle, all below a thin crust that is all we can directly see. Energy from radioactivity travels outwards as heat, producing thermal convection in the core. It seems that this convection is the cause of the earth's magnetic field, although our knowledge of the core and its dynamics is sketchy. Our knowledge is limited to saying that flow regimes like those that may be occurring in the core can produce self-sustaining dynamos, with characteristics similar to that needed to produce the earth’s magnetic field.
Explanation:
Answer:
A2/A1 = 9
V2/V1 = 27
Explanation:
Area of Sphere 1; A1 = 4πr²
Volume of Sphere 1; V1 = (4/3)πr³
Area of Sphere 2; A2 = 4π(3r)² = 9*4πr²
Volume of Sphere 2; V2 = (4/3)π(3r)³ = 27*(4/3)πr³
Thus;
A2/A1 = 9*4πr²/4πr² = 9
V2/V1 = [27*(4/3)πr³]/[(4/3)πr³] = 27
Answer:
you want to know newtons first law here.
Explanation:
An object that is at rest stays at rest or stays in motion.
Answer:
682.32 m
Explanation:
Speed of the passing speeder = 120 km/hr = 120 × 0.2777 = 33.33 m/s
time after which police man starts = 2 seconds
Acceleration of the policeman = 4.0 m/s²
let the time taken to catch be 't' seconds
Now,
The total distance to be covered by the policeman
= Distance covered by the speeder in the 2 seconds + Distance further traveled by the speeder in time t
thus,
From Newton's equation of motion
where,
s is the total distance traveled by the police man
u is the initial speed = 0
a is the acceleration
t is the time
thus,
= 33.33 × 2 + 33.33 × t
or
2t² = 66.66 + 33.33t
or
2t² - 33.33t - 66.66 = 0
on solving the above equation, we get
t = 18.47 seconds (negative value is ignored as time cannot be negative)
therefore,
the total distance covered = 33.33 × 2 + 33.33 × 18.47 = 682.32 m
Answer:
Angular momentum
Explanation:
Stars are formed as a result of a collapse of a low-temperature cloud of gas and dust. During the colapse conservation of angular momentum causes any small net rotation of the cloud to increase thus forcing the material into rotating