John is running down the street and hears dogs barking in the distance. how do the sound waves change as john approaches the barking dogs
a the height of the sound waves decreases
the height of the sound waves increases
the pitch of the sound waves changes from high to low.
ud
the pitch of the sound waves changes from low to high

Three point charges, two positive and one negative, each having a magnitude of 20 μc are placed at the vertices of an equilateral triangle (30 cm on a side). what is the magnitude of the electrostatic force on the negative charge

This is important 1. what happens to the speed of molecules in water vapor when it condenses to form a liquid? (2 points) the molecules slow down. the molecules speed up. the molecules slow down and then speed up. the molecules speed up and then slow down. 2. how might human activities change to compensate for a decrease in water supplies? (2 points) humans might build a factory. humans might build drainage systems. humans might extract more water from the ground. human behavior does not change because of the water cycle. i'll be grateful if anyone can answer these 2 questions !

How much energy must a refrigerator absorb from 225 g of water so that the temperature of the water will drop from 35°c to 5°c