Olaf is standing on a sheet of ice that covers the football stadium parking lot in buffalo, new york; there is negligible friction between his feet and the ice. a friend throws olaf a ball of mass 0.400 kg that is traveling horizontally at 10.9 m/s . olaf's mass is 70.2 kg. (a) if olaf catches the ball, with what speed vf do olaf and the ball move afterward? express your answer numerically in meters per second. (b) if the ball hits olaf and bounces off his chest horizontally at 8.10 m/s in the opposite direction, what is his speed vf after the collision? express your answer numerically in meters per second.

Search coils and credit cards. one practical way to measure magnetic field strength uses a small, closely wound coil called a search coil. the coil is initially held with its plane perpendicular to a magnetic field. the coil is then either quickly rotated a quarter-turn about a diameter or quickly pulled out of the field. (a) derive the equation relating the total charge q that flows through a search coil to the magnetic-field magnitude b. the search coil has n turns, each with area a, and the flux through the coil is decreased from its initial maximum value to zero in a time ∆t. the resistance of the coil is r, and the total charge is q = i∆t, where i is the average current induced by the change in flux. (b) in a credit card reader, the magnetic strip on the back of a credit card is rapidly “swiped” past a coil within the reader. explain, using the same ideas that underlie the operation of a search coil, how the reader can decode the information stored in the pattern of magnetization on the strip. (c) is it necessary that the credit card be “swiped” through the reader at exactly the right speed? why or why not?

Individuals who live below the poverty line get seriously ill more often than those who do not what could be the hidden variable in this situation?

1. jay fills a wagon with sand (about 20 kg) and pulls it with a rope 30 m along the beach. he holds the rope 25° above the horizontal. the rope exerts a 20-n tension force on the wagon. how much work does the rope do on the wagon?