Which statement about the universe is not correct? a) each galaxy contains billions of stars. b) the universe contains billions of galaxies. c) you may not see all stars with the naked eye. d) each solar system contains billions of galaxies.

Given the position vector of the particle r(t)=(t+1)i+(t^2−1)j+2t k, find the particle's velocity and acceleration vectors at t=1

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 causes the formation of ocean currents?