How many days will it take for the earth to orbit the sun if the sun is half its mass?

Describe the path of the electric current through a circuit?

What are similarities and differences of reflection, refraction, diffraction and absorption?

Students design a model roller-coaster track. they place a rubber ball at the highest point on the track and let it go. the ball rolls along the track pulled only by the force of gravity. eventually, it comes to a stop. which change to the design will result in the ball moving the greatest distance?