A fire truck carries a speed of 100 km/h and its siren sounds at a frequency of 900 Hz; what apparent frequency does an observer hear when he sees him approaching?

Why is there friction between objects

Which boundary is associated with the building of the himalaya mountains? convergent transform divergent hot spot

According to valence bond theory, which orbitals overlap in the formation of the bond in hf according to valence bond theory, which orbitals overlap in the formation of the bond in hf 2s on h and 2p on f 1s on h and 2s on f 1s on h and 1p on f 1s on h and 2p on f 1s on h and 3p on f