Describe the main difference between an element and a compound. Be sure to include the following ideas: pure substance, combinations, and chemical bonds.

If it takes a planet 2.8 x 10^8 s to orbit a star with a mass of 6.2 x 10^30 kg what is the average distance between the planet and the star

Aperson walking 1 mile everyday for exercise, leaving her front porch at 9: 00 am and returning to her front porch at 9: 25 am. what is the total displacement of her daily walk? a) 1 mileb) 0c) 25 minutes d) none of the above

If the ama of the inclined plane below is 2, calculate the ima and efficiency. ima = efficiency =