The average human has a density of 945 kg/m3 after inhalation, and 1020 kg/m3 after exhalation. fresh water has a density of 1000 kg/3, sea water a density of about 1025 kg/m3, and the dead sea (which is actually a lake), a density of about 1230 kg/3. which of the following statements are true?
a. the human body has nearly the same density as salt water after exhaling.
b. the human body will always float in the dead sea.
c. a human would float in fresh water after exhaling

Why does the input force have to be greater than the force needed to lift the bale?

Your target variable is δf, the magnitude of the difference in frequency between the waves emitted from the sonar device and the waves received by the device after reflecting off the whale. write an expression for δf in terms of the relevant frequencies using the subscript notation introduced above.

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?