Astar’s parallax angle is 1.0. how far away is the star in light years?

Which is the correct symbol for an isotope of iodine with 53 protons and 78 neutrons?

Aperson walks first at a constant speed of 4.89 m/s along a straight line from point a to point b and then back along the line from b to a at a constant speed of 2.95 m/s. what is the average speed over the entire trip?

If the work required to stretch a spring 3 ft beyond its natural length is 15 ft-lb, how much work is needed to stretch it 27 in. beyond its natural length?