3. One question that scientists tried to answer for many years dealt with planetary motion. How did they go about trying to determine the orbits of the planets? What were some of the models that were developed? What were the contributions of the various scientists discussed in the unit to our understandings of this topic? help me plz

Mutt and jeff are running along a path each pushing a cart loaded with rocks. if mutt's wagon has a mass two times greater than jeff's and they want to stay together, arriving at their destination at the same time, what must happen? a) jeff should slow down so mutt can catch up. b) mutt must use half as much force to push his cart. c) mutt must use twice as much force to push his cart. d) mutt and jeff will use the same force, but mutt will take bigger steps.

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

What’s #16 asking me and how do i solve it?