We've discussed elevators that are raised with cables, but many elevators use pistons. A pump provides fluid at very high pressure to the piston; the resulting force on the piston raises the elevator and passengers. For a typical piston elevator, the mass of the elevator and passengers is 2000 kg and the radius of the piston is a surprisingly small 4.2 cm. The elevator begins to move upward, accelerating at 0.80 m/s2. What is the absolute pressure in the piston?

The membrane surrounding a living cell consists of an inner and an outer wall that are separated by a small space. assume that the membrane acts like a parallel plate capacitor in which the effective charge density on the inner and outer walls has a magnitude of 7.0 × 10-6 c/m2. (a) what is the magnitude of the electric field within the cell membrane? (b) find the magnitude of the electric force that would be exerted on a potassium ion (k+; charge = +e) placed inside the membrane.

From center station, a train departs every 30 minutes on the fast line and a train departs every 50 minutes on the state line. if two trains depart from center station at 8: 00 a.m., one on each of the two lines, what is the next time that two trains, one on each line, will depart at the same time?

Because light travels in a straight line and casts a shadow, isaac newton hypothesized that light is