You click your fingers in a large hall and hear the echo 0.5 seconds later off the back wall. How far is the back wall? A boat send a sound to the bottom of the ocean and it takes 2 seconds to return to the boat. How deep in the ocean?

Please answer the questions above for 15 points, help desperately needed!:)

An ambulance emits a frequency of 450 hz from its siren. what frequency is heard by a man as the ambulance moves toward him? less than 450 hz more than 450 hz 450 hz 0 hz

What are atoms of the same element with varying number of neutrons

Two resistors r1 and r2 may be connected either in series or parallel across an ideal battery with emf ε. we desire the rate of energy dissipation of the parallel combination to be 8.75 times that of the series combination. if r1 = 105 ω, what are the (a) smaller and (b) larger of the two values of r2 that result in that dissipation rate?