Standing waves of frequency 68 hz are produced on a string that has mass per unit length 0.0160 kg/m. with what tension must the string be stretched between two supports if adjacent nodes in the standing wave are to be 0.74 meters apart?

Assume you measured the mass of the cart to be (500 ± 1) g and the mass of the additional mass you put on the cart to be (500 ± 1) g as well. since the scale you are using in the lab cannot measure objects heavier than 600g you will have to sum up individual pieces and propagate the error. so what would be the mass and the standard error of the cart and the mass

What sort of waves exhibit the doppler effect?

Newtons view of arrangement of the universe. don't copy from anywhere.