A person is lifted 24 meters by the elevator in a building. If the person has a mass of 74 kg, what is the gravitational potential
energy gained by the person? Estimate g to 9.81 and keep 5
significant figures.

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.

If gases like carbon dioxide and methane make up less than 1% of the total atmosphere, why is it important for scientists to monitor changes in percentages of these gases?

Notice how they put future which of the clouds shown would indicate a possible future rain storm? a) b) c) d)