Which of the following statements is true about our galaxy?

it contains one star.
it contains several stars.
it contains several thousand stars.
it contains billions of stars.

Use the data provided to calculate the gravitational potential energy of each cylinder mass. round your answers to the nearest tenth. 3 kg: kj 6 kg: kj 9 kg: kj

One day, after pulling down your window shade, you notice that sunlight is passing through a pinhole in the shade and making a small patch of light on the far wall. you see that the patch of light seems to be a circular diffraction pattern. it appears that the central maximum is about 1 cm across and you estimate that the distance from the window shade to the wall is about 3 m. what is (a) the average wavelength of sunlight? (b) the diameter of the pinhole?

What is the magnitude of the resultant vector round your answer to the nearest tenth