# Yahoo Web Search

1. ### A 633 nm helium -neon laser puts out 6.00 W of power with a beam 6.00 mm in diameter. The beam is pointed directly at a pinhole ?

per photon, E = hc/λ = 6.626e-34kg·m²/s * 3e8m/s / 633e-9m E = 3.14e-19 J power through the hole is P = 6.00J/s * (1.60/6.00)² = 0.427 J/s 0.427J/s / 3.14e-19J/photon = 1.36e18 photons / s If you find this helpful, please select...

1 Answers · Science & Mathematics · 16/11/2020

2. ### how much lighter is a vacuum than hydrogen?

Hydrogen gas at STP has a density 0f 0.08988 g/L = 5.611 lbs / 1000 cubic feet. So 1000 cubic feet of vacuum could life 68 + 5.6 = 73.6 pounds. Problem is, hydrogen gas pushes out on its container, so the balloon can...

1 Answers · Science & Mathematics · 21/11/2020

3. ### A skydiver is descending with a constant velocity. Make a free-body diagram of all the forces acting on the skydiver. ?

...buoyancy acting upwards.  (This is the force that makes a helium balloon rise for example.) So if I were answering I...

2 Answers · Science & Mathematics · 19/11/2020

4. ### physics questions?

...emission (γ-emission) Q3. An alpha particle which is the same as a helium nucleus (consisting of 2 protons and 2 neutrons). A...

1 Answers · Science & Mathematics · 20/11/2020