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

Explain vector addition, triangle method and parallelogram method

(2) (a) you have a simple circuit that consists of only a battery (δvbat=1.5v) and two resistors with resistance r1=10ω and r2=5ω, connected in series with each other. what is the current running through the battery? (b) you re-arrange your circuit so now r2 is attached in parallel to r1 rather than in series. what is the current running through the battery? (c) you add an additional resistor r3=7ω on the same branch as r2. what is the current running through the battery? (d) what is the power dissipated in r3?