7. A 2.5 kg ball moving at 4.2 m/s collides with a 2.5 kg stationary ball. If the first ball is at rest after the collision, what is the velocity of the second ball? a 2.1 m/s​

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

Which of the following are guidelines to follow for obtaining accurate observations

Jenny wants to test the electrical conductivity of two substances dissolved in water. she is preparing the containers for the experiment. which factor is most important for her to control? a) volumes of the solutions b) appearance of the solutions c) temperatures of the solutions d) concentrations of the solutions