You purchased a new set noise-cancelling headphones to wear on your plane ride to hawaii last month. the intensity of the background noise on the plane (prior to wearing the headphones) was 4 x 10-2 w/m2. when wearing the headphones, the intensity of the noise was reduced to 2 x 10-3 w/m2. how much noise reduction (in db) did the headphones provide?

The of a machine determines its "usefulness." a. input force b. output force c. mechanical advantage

How can you increase the strength of an electromagnet?

One hazard of space travel is debris left by previous missions. there are several thousand masses large enough to detect by radar orbiting the earth, but there are far greater numbers of very small masses such as flakes of paint. calculate the force exerted by a 0.110 mg chip of paint that strikes a space shuttle window at a relative speed of 5.00 ✕ 103 m/s and sticks, given the collision lasts 6.00 ✕ 10-8 s. such a collision chipped the window of the ill-fated challenger in june 1983, causing $50,000 of damage.