Answer:
The answer is β=0,85 rads
Explanation:
As the ladder is leaning against the building, we can imagine there´s a triangle where 20ft is the hypotenuse and 15ft is the maximum vertical distance between the ladder and the ground, it means, the leg opposite to β which is the angle we need
Let β(betha) be the angle between the ladder and the ground
We also know that 
In this case we will need to find β, this way:

Then β=48,6°
We also have that 2πrads is equal to 360°, in this way we find how much β is in radians:

then we find β=0,85rads
Answer:
Millions of years.
Explanation:
Fossil fuels are fuels formed by natural processes. It involves decomposition of dead and decaying animals, marine and plants for over million years. This some times take more than hundred million years to convert into fuel. This is why they are called non renewable resources of energy. The decomposition of dead plant species forms coal and decomposition animals of land and sea forms crude oil and gas.
Answer:
Explanation:
The motion of Mary along the circular path is a centripetal.
As Mary moves from one edge of the circular platform to the other edge, she is covering a distance which is the radius of the circular path at a velocity.
According to the relationship
w = v/r where
w is the angular velocity
r is the radius
v is the linear velocity
Initially, before Mary starts, her linear speed is zero and her angular velocity is also zero. As she move towards the opposite edge, she is covering a distance of radius r. According to the formula, increase in radius will leads to decrease in her angular velocity and vice versa. As Mary starts moving towards the centre of the circular path, her angular velocity increases, at the centre of the platform, her angular velocity is at maximum at this point. As she moves further from the center to the other edge, her angular velocity decreases due to increase in distance covered across the circular path.
A cloud in space that is composed of dust and gas is call a nebula. The word "nebula" is derived from the Latin word for "cloud," and nebulae in space are indeed large interstellar clouds made up of dust, hydrogen, helium and plasma.