The block moves with constant velocity: for Newton's second law, this means that the resultant of the forces acting on the block is zero, because the acceleration is zero.
We are only concerned about the horizontal direction, and there are only two forces acting along this direction: the force F pushing the block and the frictional force

acting against the motion. Since their resultant must be zero, we have:

The frictional force is

where

is the coefficient of kinetic friction

is the weight of the block.
Substituting these values, we find the magnitude of the force F:
UV rays have the lowest energy, (highest wavelengths)
1. 2504.63 J
2. 929.5m/s
Hope this helps :)
I can explain it as well if you’d like
Answer:
static
Explanation:
static friction pushes in the direction you are walking.
Answer:
(1) A sound wave a mechanical wave because mechanical waves rely on particle interaction to transport their energy, they cannot travel through regions of space that are void of particles. Sound is a mechanical wave and cannot travel through a vacuum. These particle-to-particle, mechanical vibrations of sound conductance qualify sound waves as mechanical waves. Sound energy, or energy associated with the vibrations created by a vibrating source, requires a medium to travel, which makes sound energy a mechanical wave. The answer is(B) it travels in the medium.
(2) An ocean wave is an example of a mechanical transverse wave
The compression is the part of the compressional wave where the particles are crowded together. The rarefaction is the part of the compressional wave where the particles are spread apart. The answer is (C) Compression.