The increase in resistant strains of insects to chemicals is a result of:

I need these for test corrections that are due tomorrow please :)

Ivahew [28]

That would be position Y, as the northern hemisphere is tilted away from the sun.

6 0

4 years ago

Why can the structure of the solar system be compared to soap bubbles?

lukranit [14]

Because the universe is sort of like the surface of a balloon just like soap bubbles. The reason for this, is because of all the clusters and superclusters that are found within the bubble walls. Hope that helps!

7 0

3 years ago

Determine the two coefficients of static friction at B and at C so that when the magnitude of the applied force is increased to

stiks02 [169]

Now, there is some information missing to this problem, since generally you will be given a figure to analyze like the one on the attached picture. The whole problem should look something like this:

"Beam AB has a negligible mass and thickness, and supports the 200kg uniform block. It is pinned at A and rests on the top of a post, having a mass of 20 kg and negligible thickness. Determine the two coefficients of static friction at B and at C so that when the magnitude of the applied force is increased to 360 N , the post slips at both B and C simultaneously."

Answer:

$\mu_{sB}=0.126$

$\mu_{sC}=0.168$

Explanation:

In order to solve this problem we will need to draw a free body diagram of each of the components of the system (see attached pictures) and analyze each of them. Let's take the free body diagram of the beam, so when analyzing it we get:

Sum of torques:

$\sum \tau_{A}=0$

$N(3m)-W(1.5m)=0$

When solving for N we get:

$N=\frac{W(1.5m)}{3m}$

$N=\frac{(1962N)(1.5m)}{3m}$

$N=981N$

Now we can analyze the column. In this case we need to take into account that there will be no P-ycomponent affecting the beam since it's a slider and we'll assume there is no friction between the slider and the column. So when analyzing the column we get the following:

First, the forces in y.

$\sum F_{y}=0$