A man jumps from an airplane and does not open his parachute immediately. As he falls,
two forces act on him: the force mg due to
gravity and the force n, of air resistance. Now
he opens his parachute and begins to fall at
constant velocity.
What forces act upon him now?
1. Since he is falling at constant velocity
gravity no longer acts on him.
2. None of these
3. Since he is falling at constant velocity the
force of air resistance no longer acts on him.
4. The same two forces act on him as before;
the only change is that with the parachute
open, the two forces sum to zero.
5. When the parachute opens there is an
additional force n, which has nothing to do
with either n, or mg

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?

Employer informs its employees that it will hold a substantial cash prize drawing for each work group at the end of each month in which no employee in the work group sustains a lost-time injury. tyra reports an injury that she sustained while operating a mechanical power press. tyra did not violate any employer safety rules when she sustained her injury. tyra’s injury requires her to miss work for two days. her employer cancels the cash prize drawing for that month for tyra’s work group because of tyra’s lost-time injury. did the employer misuse an incentive program to retaliate against tyra?

Atemperature of 50°f is equal to °c.