The length, s, (in feet) of the skid mark left by an automobile traveling at r miles per hour can be approximated by the relation r=25s−−√. at the scene of an accident, police measured a skid mark of 361 feet. about how many miles per hour was the car traveling when the brakes were applied?

The radioactive isotope of lead, pb-209, decays at a rate proportional to the amount present at time t and has a half-life of 3.3 hours. if 1 gram of this isotope is present initially, how long will it take for 80% of the lead to decay? (round your answer to two decimal places.)

50.)the diagram below represents the wave fronts produced by a point source moving to the right in a uniformmedium. observers are located at points a and b.compared to the wave frequency and wavelength observed at point a, the wave observed at point b has a(1) higher frequency and a shorter wavelength(2) higher frequency and a longer wavelength(3) lower frequency and a shorter wavelength(4) lower frequency and a longer wavelength

What is "decrease in velocity" i need offering 60 !