There is a parlor trick in which person#1 hangs a dollar bill from their hand so that it dangles between the fingers of person#2. person#1 releases the bill, and person#2 must try to close their fingers in time to catch the bill before it falls completely through their fingers. the length of the bill is 15.6 cm and a typical person's reaction time is 0.20 seconds. the typical person will not be able to catch the bill. calculate how fast a person's reaction time would have to be to just barely catch the falling bill (assume that you can neglect air friction).

Aregion of space in which a measurable gravitational force is indicated by the force exerted on a test mass is called

For the car in the picture ,in which direction is the normal force? -into the screen -down -out of the screen -up

An alpha particle with kinetic energy 12.5 mev makes a collision with lead nucleus, but it is not "aimed" at the center of the lead nucleus, and has an initial nonzero angular momentum (with respect to the stationary lead nucleus) of magnitude l = p0 b, where p0 is the magnitude of the initial momentum of the alpha particle and b=1.40×10−12 m. (assume that the lead nucleus remains stationary and that it may be treated as a point charge. the atomic number of lead is 82. the alpha particle is a helium nucleus, with atomic number 2.) what is the distance of closest approach?