B. If we drop a ball from the roof, its falls
downward

Achlorine atom has 17 protons and 18 neutrons. what is its mass number? what is its atomic number?

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

Need only answer if you think you know it