What is the name of the line drawn perpendicular to the surface where a light ray strikes?

Examine the equation. 23490th→23088ra+42he what kind of barrier would you need to block the radioactive particles from this reaction? a.a piece of paper b.a sheet of aluminum foil c. a two-inch block of lead d. a solid concrete block

1.what is where an object is located 2. what is how fast an objects speed is changing 3. what is how fast an object is moving

Considering only the earth's rotation, determine how much later the asteroid would have had to arrive to put the explosion above helsinki at longitude 25˚ e? this would have obliterated the city.