What is the force applied to a baseball that has a mass of 142kg and has a acceleration of 30m/s to the power of 2

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?

Two loudspeakers, 5.5 m apart and facing each other, play identical sounds of the same frequency. you stand halfway between them, where there is a maximum of sound intensity. moving from this point toward one of the speakers, you encounter a minimum of sound intensity when you have moved 0.33 m . assume the speed of sound is 340 m/s. part a) what is the frequency of the sound? part b) if the frequency is then increased while you remain 0.21 m from the center, what is the first frequency for which that location will be a maximum of sound intensity? express your answer to two significant figures and include the appropriate units.

When using the scientist method, which step comes last?