What is the speed of sound in metro city if the temperature is 26 degree celsius ?

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 happens to an isotope during radioactive decay?

How does the strength of the electrostatic force between an electron and a proton compare to the strength of the gravitational force between them?