15) C. The amount of each element that begins....
Answer:
The correct option is;
c. 45°
Explanation:
The given information is that the angle the vector makes with the horizontal = θ
Let the magnitude of the resultant vector = R
The horizontal component of the vector are given as follows;
Rₓ = R × cos(θ)
The vertical component of the vector are given as follows;
= R × sin(θ)
The resultant vector, R, in vector form, R, is the sum of the horizontal and vertical components as follows;
R = R × cos(θ)·i + R × sin(θ)·j
Therefore;
The horizontal and vertical component will be equal when cos(θ) = sin(θ)
Given that tan(θ) = sin(θ)/cos(θ), we have that when cos(θ) = sin(θ), tan(θ) = sin(θ)/cos(θ) = sin(θ)/sin(θ) = 1
tan(θ) = 1,
∴ θ = tan⁻¹(1) = 45°
θ = 45°.
Answer:
Physical changes only change the appearance of a substance, not its chemical composition. Chemical changes cause a substance to change into an entirely substance with a new chemical formula. Chemical changes are also known as chemical reactions.
Find stress using the formula Stress = Force / Area. Here, force
exerted by 85kg person on stool is F = mg = 85kg * 9.8 m/s^2 = 833N. Find total
area of 3 legs A = 3 π (D/2)^2 = 3 π (2.5 x 10^-2 / 2)^2 = 1.4726 x 10^-3 m^2.
Now substitute in Stress = Force/Area. Stress = 833N / 1.4726 x 10^-3 m^2 =
5.656 x 10^5 N/m^2. Find strain using the formula strain = Stress / Young’s
modulus. For wood, Y = 1.3 x 10^10 N/m^2. Thus, strain = 5.656x10^5 N/m^2 /
1.3x10^10 N/m^2 = 4.35 x 10^-5 = 0.00435%.
Therefore, the legs decrease by 0.00435%
Answer:
Noble gases are nonreactive elements.
Explanation:
We call Group 18 of the Periodic Table "Noble gases" because they are inert gases. They do not like to bond with other elements.
The reason why is because their outermost shell for electrons is full. These electrons, called valence electrons, are are completely maxed out and therefore makes the element stable. This in turn makes it so that it doesn't really bond with other elements.
