Can anyone just check my answers and tell me if correct or not. if i’m incorrect, tell me the correct on a windless day, train a is traveling down a grade at 50 m/s and passes train b, which is moving up the grade at half that speed. after the trains pass, train a blows it’s 300 hz whistle. what frequency is heard by a passenger on train b. 312 hz 435 hz 243 hz(my choice) 186 hz a police officer parked at the curb turns on his lights and siren, waits for traffic to clear, then pulls out and heads down the street. for an observer down the street, which is true? the frequency of the siren is higher and the wavelength is shorter than it was at first. the wavelength of the siren is shorter than it was at first, but the frequency is the same(my choice) the wavelength of the siren is shorter and the frequency is lower than it was at first. the frequency of the siren is higher than it was at first, but the wavelength is the same

What tightening torque should be used for a hexagonal head screw (not split-bolt) on a 250 kcmil conductor?

The frequency of vibrations of a vibrating violin string is given by f = 1 2l t ρ where l is the length of the string, t is its tension, and ρ is its linear density.† (a) find the rate of change of the frequency with respect to the following. (i) the length (when t and ρ are constant) (ii) the tension (when l and ρ are constant) (iii) the linear density (when l and t are constant) (b) the pitch of a note (how high or low the note sounds) is determined by the frequency f. (the higher the frequency, the higher the pitch.) use the signs of the derivatives in part (a) to determine what happens to the pitch of a note for the following. (i) when the effective length of a string is decreased by placing a finger on the string so a shorter portion of the string vibrates df dl 0 and l is ⇒ f is ⇒ (ii) when the tension is increased by turning a tuning peg df dt 0 and t is ⇒ f is ⇒ (iii) when the linear density is increased by switching to another string df dρ 0 and ρ is ⇒ f is ⇒

Awater slide of length l has a vertical drop of h. abby's mass is m. an average friction force of magnitude f opposes her motion. she starts down the slide at initial speed vi. use work-energy ideas to develop an expression for her speed at the bottom of the slide. then evaluate your result using unit analysis and limiting case analysis. express your answer in terms of the variables h, m, l, vi, f and appropriate constants. vf v f