8. a train rolls at a constant speed of 10 m/s across a horizontal track. a child standing on the flatbed of the
train throws a ball so that it appears to move straight up to an observer standing next to the track.
a. what is the horizontal speed of the ball relative to the observer?
b. what is the horizontal speed of the ball relative to the train?
c. if the ball is also thrown upward with a speed of 20 m/s, what is the overall initial speed of the ball
relative to the train?

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.

Acar moves a distance of 50.0 km west, followed by a distance of 64.9 km north what was the magnitude of the displacement of the car, in units of kilometers?

Ascientist notices that an oil slick floating on water when viewed from above has many different colors reflecting off the surface, making it look rainbow-like (an effect known as iridescence). she aims a spectrometer at a particular spot and measures the wavelength to be 750 nm (in air). the index of refraction of water is 1.3