Amotion sensor acts as a transmitter when it sends out pulses and as a receiver when it listens for echoes. the delay ∆t between sending the pulse and receiving the echo is equal to 8.9 ms. the air temperature is equal to 20º c. part a what is the distance between the motion sensor and the object?

You have been hired to design a spring-launched roller coaster thatwill carry two passengers per car. the car goes up a 10-m highhill, then descends 15m to the track's lowest point. you'vedetermined that the spring can be compressed a maximum o 2.0m andthat a loaded car will have a maximum mass of 400kg. for safetyreasons, the spring constant should be 10% larger than the minimumneeded for the car to just make it over the top. a) what spring constant (k) should you specify ? b) what is the maximum speed of a 350 kg car if the spring iscompressed the full amount.