PLS HELP !! Which of these must be true for a perfectly elastic collision?

Select one:

A: Kinetic energy is conserved
B: The velocity of the first object will not transfer to the second object
C: The objects will stick together
D: The masses must be equal​

Rank the torques on the five doors shown in the figure above from least to greatest. note that the magnitude of all the forces is the same

Electric charge is uniformly distributed inside a nonconducting sphere of radius 0.30 m. the electric field at a point p, which is 0.50 m from the center of the sphere, is 15,000 n/c and is directed radially outward. what is the maximum magnitude of the electric field due to this sphere

Although light from the sun appears white, it is actually made up of a lot of different colors. this portion of the electromagnetic spectrum, we call white light is referred to as within the electromagnetic spectrum.