A lens has a radius of curvature of magnitude R R on its left surface and a radius of curvature of magnitude 2R 2 R on its right surface. Parallel rays entering the lens from the left are focused to a point 145 mm m m to the right of the right surface.

If a clock aboard a space ship traveling at 0.900 c of the speed of light relative to earth chimes once at the beginning of the hour and again when it reads one hour later, how much time would an observer on earth say elapsed between the two chimes?

Which sentences describe disadvantages of burning fossil fuels instead of using hydrogen fuel cells? burning fossil fuels contributes to climate change. burning fossil fuels takes place inside expensive fuel cells. fossil fuels aren't widely available, but pure hydrogen is. fossil fuels are nonrenewable.

Which statement best describes how private industry decides where to spend the money on research and development