The spontaneous emission of radiations from an unstable nuclei is known as natural radioactivity. on the other hand, The process of emission of radiations from naturally occurring isotopes when they are bombarded with sub-atomic particles or high levels of X-rays or gamma rays called artificial radioactivity.
Answer:
0.04455 Hz
Explanation:
Parameters given:
Wavelength, λ = 6.5km = 6500m
Distance travelled by the wave, x = 8830km = 8830000m
Time taken, t = 8.47hours = 8.47 * 3600 = 30492 secs
First, we find the speed of the wave:
Speed, v = distance/time = x/t
v = 8830000/30492 = 289.58 m/s
Frequency, f, is given as velocity divided by wavelength:
f = v/λ
f = 289.58/6500
f = 0.04455 Hz
Answer:

Explanation:
We know the mass of the hole, so we define as,
kg
For which centripetal force is equal to gravitational force

Angular velocity is equal to v/r,

As r=1 and w=1, we clear to d,
m

Answer:
mutualism
Explanation:
Mutualism, a relationship in which both species benefit, is common in nature. In microbiology, there are many examples of mutualistic bacteria in the gut that aid digestion in both humans and animals.
The force that a moving object exerts on another object upon colliding with it is rather the change in momentum divided by the amount of time elapsed during the collision.
F = Δp/Δt
F = force, Δp = change in momentum, Δt = elapsed time
Usually we say momentum is proportional to mass instead of saying momentum is proportional to weight. But sure, for two objects on the same planet, greater weight implies greater mass. Momentum is the product of mass and velocity:
p = mv
p = momentum, m = mass, v = velocity
So we have two identical cars on the same planet with one car traveling 30mph faster than the other. Let's say they both collide with a tree, both coming to a rest, and the collisions take the same amount of time to happen. The faster car loses a greater amount of momentum over the same amount of time, therefore delivering a greater force.
Choice B