First, you make a force body diagram to illustrate the problem. Then, apply Newton's laws of motion.
Summation of forces along the y-direction:
F = 0 (bodies at equilibrium) = Normal force - weight*cos45 = 0
Normal force = wcos45
Summation of forcesalong the x-direction:
F = 0 (bodies at equilibrium) = Frictional force - weight*sin45 = 0
x*Normal force - weight*sin45 = 0 (let x be the min coeff of static friction)
x*weight*cos45 = weight*sin 45
x = sin45/cos45 = 1
Therefore, the minimum coefficient of static friction must be 1.
the orbit of the moon around earth causes the phases since the light from the moon is caused by a reflection of sunlight... btw wrong subject,....
Answer:
No electromagnetic waves can not exists if changing magnetic field could produce electric fields but the changing electric fields could not produce magnetic fields. Electromagnetic waves are oscillating waves and they are based on this fact that the changing magnetic field produce electric field and the changing electric field produce the magnetic field. That is why these waves are known for self propagation and can even travel through vacuum. In this wave the electric field and the magnetic field lies perpendicular to each other. These waves travel with the speed of light and their example is light and other radiations coming from sun.
The correct answer is:
<span>Point charges must be in a vacuum.
In fact, the usual form for of the Coulomb's law is:
</span>

<span>where
</span>

is the permittivity of free space
<span>q1 and q2 are the two charges
q is the separation between the two charges
However, this formula is valid only if the charges are in vacuum. If they are in a material medium, the law is modified as follows:
</span>

where

is the relative permittivity, which takes into account the dielectric effects of the material.