Avolleyball player hit he ball with a mass of .25 kg. the average acceleration of the ball is 15.5 m/s^2. how much force did the volleyball player apply to the ball?

Wo audio speakers are placed on a vertical rail. speaker a is placed at head-level while speaker b is place at some variable height, \delta yδy, above speaker a. both speakers receive simultaneous input from a sine-wave generator so the speakers each produce a pure sinusoidal sound wave with a wavelength of 0.531 meters. calculate the lowest height that speaker b can be placed above speaker a to produce a minimum of sound heard by person standing \delta x = 7.86δx=7.86 meters directly in front of speaker a.

This is for my 8th grade science class, i really don’t understand. can someone me? , lol.

Which additional product balances the reaction h2so4 + 2naoh → na2so4 + 2h2o 2oh h2o2 h3o