A new piece of exercise equipment has been added to your gym, and you try it out. To use this machine, you lie horizontal on a mat with your feet against a platform perpendicular to the mat. The platform is held by a stiff spring that is compressed when the platform moves. Your workout invovles compressing the spring by pushing on the platform with your feet. After testing compressions of the equipment, you determine that you must do 85.0 J of work to compress the spring a distance 0.170 m from its uncompressed length. What magnitude of force must you apply to hold the platform stationary at the final distance given above

*drag each tile to the correct location in the sequence* the table shows chronological events in the life of our sun, a medium-sized star. place the missing events into the correct rows of the table.

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?

This is the substance(s) formed in a chemical reaction.