Recent content by pinkerpikachu

1. How many helium balloons does it take to lift a person?

Wait, I have the density of the air and the helium switched, right? The buoyant force is due to the air and not the helium? Because the air is the fluid that it is in? This is probably an easy question, but I'm pretty sleep deprived haha
2. How many helium balloons does it take to lift a person?

Homework Statement How many helium-filled balloons would it take to lift a person? Assume the person has a mass of 76 kg and that each helium-filled balloon is spherical with a diameter of 33 cm. Homework Equations P = P0 + ρgV The Attempt at a Solution I really don't know why this is...
3. Snell's Law and Lasers

I see, the two diameters are related through the common interface (the hypothenuse of the two triangles). Just some geometry from there. It makes sense, thank you :)
4. Snell's Law and Lasers

Homework Statement A laser beam of diameter = 3.1mm in air has an incident angle = 26 degrees at a flat air-glass surface.If the index of refraction of the glass is n=1.5, determine the diameter of the beam after it enters the glass. Homework Equations n1sinθ1=n2sinθ2 The Attempt...
5. Optimization Problems

Homework Statement If you can help me answer ANY of these, it will be very appreciated. thanks in advance. 1. The following problem was stated and solved in the work Nova stereometria vinariorum, published in 1615 by the astronomer Johannes Kepler. What are the dimensions of the cylinder...
6. Volume using the disk method

Homework Statement Use the functions: y=x+1, y=0, x=0, x=2 Find the volume when rotated around y=3 Find the volume when rotated around y=-1 Homework Equations PI\int R2dx or perhaps PI\int R2 - r2dx The Attempt at a Solution i don't think that this is a particularly hard question, but I...
7. Special relativity Problem

nevermind! totally solved my own problem!
8. Special relativity Problem

The fictional starship Enterprise obtains power by combining matter and antimatter, achieving complete conversion of mass into energy. If the mass of Enterprise is approximately 5 X 109 kg, how much mass must be converted into kinetic energy to accelerate it from rest to one tenth the speed of...
9. Special relativity - What if the speed of light was infinite?

I have very limited knowledge of taking limits. Um...is it undefined or zero? I took some notes in class, and for length contraction I have the formula and then: as v --> c, L --> 0 oh wait! I forgot there was a one in the formula. So if v^2/ c^2 is just a really small number, then 1 minus that...
10. Special relativity - What if the speed of light was infinite?

Sorry, I wouldn't just ask for an answer like that if had any idea of how to solve it. Special relativity just blows my mind and I was hoping to clear up a few things in my brain with the answer to these questions. But here goes nothing: Okay. So, length contraction, the equation is...
11. Special relativity - What if the speed of light was infinite?

Special relativity -- What if the speed of light was infinite? Suppose the speed of light was infinite. What would happen to the relativistic predictions of length contraction and time dilation? Okay, so I know all of this is based on the concept of the constancy of the speed of light. So...
12. The gravitational slingshot effect

Okay, as the aircraft approaches Saturn, its going to feel some kind of gravitational pull towards the larger body. Correct? This pull is a force which is stated as conservative. So will it have an impact on the final speed on the air craft? Will this force slow down the aircraft? I know a...
13. The gravitational slingshot effect

The gravitational slingshot effect. In the diagram below, the planet Saturn moving in the negative xdirection at its orbital speed (with respect to the Sun) of 9.6 km/s. The mass of Saturn is 5.96 × 1026 kg. A spacecraft with mass 825 kg approaches Saturn. When far from Saturn, it moves in the...
14. Electric Potential Questions!

1. If V= 0 at a point in space, must E=0 there? If E=0 at some point must V=0 at that point? And examples for each? I'm pretty confused on both parts. I haven't really been understanding much of this electric charge/electric field stuff. I know, just from an equation at V= -Ed, but I...
15. 2D kinematics? Have equations but making errors?

When Babe Ruth hit a homer over the 7.5-m-high right-field fence 95 m from home plate, roughly what was the minimum speed of the ball when it left the bat? Assume the ball was hit 1.0 m above the ground and its path initially made a 38º angle with the ground 2. Vx= Vcosθ...