The diffraction grating and the hydrogen spectrum

Physically, what does the 2 corresponded to in the balmer series equation? What does the n correspond to?

Understanding why it is not possible for humans to runs up walls. Complete with a solution diagram.

Why can't a person just walk or run up a wall? What is keeping them from performing this task? Which formula, would best describe what is going on?

Optics

1. A point source of light lies on the central axis of a bi-convex spherical lends who radii of curvature are both measured to be 19.4 cm. The lens is made up of glass with an index of refraction of 1.50 and the source is 3.17 meters to the left of it. What is the image distance (in meters)? 2. A grasshopper sitting 31.4 cm to the left of a convex lends sees its image on a screen 68.6 cm to the right of the lens. It then jumps 16.2 cm toward the lens. Where will its image be now? 3. A point source is moved along the central axis of a thin spherical glass (n=1.5) lens, and it is found that when the source is at 10.1 cm from the lens the emerging light forms a perfectly cylindrical bea... click for more

Working with circular motion and centripetal acceleration.

There is a hand held device with a rod with a cord attached to a spring scale on the rod. You swing the ball around in a horizontal circle with a radius of 0.500 m. There are several parts to this that I need help with. If the speed of the ball is 3.7 m/s, how do you calculate the expected tension in the cord? Why can't you swing the ball so the cord remains exactly horizontal? How do you calculate the angle the cord makes?

Debating on whether Pluto is planet or not.

Argue against the fact that Pluto shouldn't be considered a planet.