What is the acceleration of a penny as it falls if it is dropped from rest and hits the ground 3 seconds later at a speed of 29.4 m/s?

Atrain departs from its station at a constant acceleration of 5 m/s. what is the speed of the train at the end of 20s?

Ajet plane has a sound level of 120 db at a distance of 60 m. what is the q23. sound level at a distance of 6.0 km? (60)2 (6000)? om solution 80db db, hint: 16x assume ultrasound waves travel through the body of an animal at 1540 q24. m/s. if a 30,000 hz signal were reflected off a portion of a heart which was moving toward the source at 3 m/s, what frequency signal would return to the stationary source? solution 30.117hz

The air that we breath is made mostly of which gaseous molecule