Why do roads leading to the top of a mountain wind back and forth

What happens in a global convection cell

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

While the change in blank will remain the same during a collision, the force needed to bring an object to a stop can be blank if the time if collision is blank