The kelvin temperature/scale i think
A mechanical wave<span> requires an initial energy input. Once this initial energy is added, the </span>wave travels through<span> the medium until all its energy is transferred.</span>
Answer:
Spiral galaxies consist of a flat, rotating disk of stars, gas and dust, and a central concentration of stars known as the bulge. These are surrounded by a much fainter halo of stars, many of which reside in globular clusters.
Elliptical galaxies have smooth, featureless light-profiles and range in shape from nearly spherical to highly flattened, and in size from hundreds of millions to over one trillion stars. In the outer regions, many stars are grouped into globular clusters. Most elliptical galaxies are composed of older, low-mass stars, with a sparse interstellar medium and minimal star formation activity They are often chaotic in appearance, with neither a nuclear bulge nor any trace of spiral arm structure. Collectively they are thought to make up about a quarter of all galaxies.
irregular galaxies were once spiral or elliptical galaxies but were deformed by gravitational action. they are shapeless.
Answer:
1. 218.55 N
2. 
3. 
Explanation:
Part 1;
Net force 
where m is mass, g is gravitational force and 
is the angle of inclination
Frictional force, 
is given by
where 
is the coefficient of static friction
Since 
, therefore, the block doesn’t slip and the frictional force acting is mgh=218.55N
Part 2.
Using the relationship that
Frictional force 
The maximum angle of inclination 
Part 3:
Net force on the object is given by
where 
is the coefficient of kinetic friction
= 9.8 ( sin 38 - (0.51) cos 38 )
= 
Answer:
Electric Field intensity is zero.
The reason for that is:
All charges are placed at equal distances from the center of the square and have same magnitude and sign. This means they will exert equal and opposite forces on the test charge at the center. Net force will become Zero.
