For example, if a buyer obtains a seven-year balloon mortgage to purchase a home, he has seven years of equal monthly payments at a fixed interest rate. This rate is often lower than what the buyer would otherwise be able to secure under a traditional mortgage loan.
When sound reflects off a special curved surface called a parabola, it will bounce out in a straight line no matter where it originally hits. Many stages are designed as parabolas so the sound will go directly into the audience, instead of bouncing around on stage.
Thin Shock Layers: Students of aerodynamics know that when a supersonic flow passes over a wedge, a shock wave will form at the point of the wedge. This kind of shock wave is called an oblique shock because it forms at some angle to the surface of wedge (a shock wave perpendicular to the surface is known as a normal shock).