it would be a chain reaction and a wave
21. light changes its direction when travelling through a new medium because denser mediums have a higher angle of refraction.
The only vertical forces are weight and normal force, and they balance since the surface is horizontal. The horizontal forces are the applied force (uppercase F) in the direction the block slides and the frictional force (lowercase f) in the opposite direction.
Apply Newton's 2nd Law in the horizontal direction:
ΣF = ma
F - f = ma
where f = µmg
F - µmg = ma
F = m(a +µg)
F = (20 kg)(1.4 m/s² + 0.28(9.8 m/s²)
F = 83 N
Answer:
Magnetic fields exist near a magnet, farther away from a magnet, and within a magnet.
So, the answer is D. All of the above.
Let me know if this helps!