6. The fire-security system of the buildings will be activated if the internal temperature passes 140 [°F]. The siren will make a sound with frequency 915 [Hz]. What will be the frequency of the sound heard by the observer who moves toward the building with the speed 5 [m/s]. The average speed of the sound in the air: 340 [m/s]. Round the result to the nearest tenth.

The rigid beam is supported by the three suspender bars. bars ab and ef are made of aluminum and bar cd is made of steel. if each bar has a cross-sectional area of 450 mm2, determine the maximum value of p if the allowable stress is (σallow)st = 200 mpa for the steel and ( σallow)al = 150 mpa for the aluminum. est = 200 gpa and eal = 70 gpa.

An object moves from the position +34m to the position -15m in 15 seconds. what is it's total displacement? what is it's average velocity?

Part 1: a magnetic levitation or maglev train rides rails without touching them. explain how this works using your data. include the appropriate magnet drawing in your answer. part 2: two objects are near a bar magnet. one is about 1 cm away, while the other is 6 cm away. compare and contrast the magnetic force that affects each object. use your data to answer the question