Amagnetic hockey puck (0.40 kg) hits another hockey puck (0.40 kg) at rest and both travel together to the right at 8.0 m/s. how fast was the first hockey puck initially moving?

Ineed the answer to question 1 , i’m desperate

The sound level near a noisy air conditioner is 70 db. if two such units operate side by side, the sound level near the, would bea. 70dbb. 73 dbc. 105 dbd 140 db

Using proper grammar, spelling, and punctuation, write at least one 5 sentence paragraph describing 3 ways we use the elements of the electromagnetic spectrum (ems) in our everyday lives.