Arunaway railroad car, with mass 30x10^4 kg, coasts across a level track at 2.0 m/s when it collides with a spring loaded bumper at the end of the track. if the spring constant of the bumper is 2x10^6 n/m, what is the maximum compression of the spring during the collision? (assume collision is elastic)

Sarah and michelle work at a tech company that designs exercise apps. sarah tells michelle she has heard that james, their supervisor, interviewed with a competitor and may be leaving the company, which would open up a management position. what kind of power is sarah exerting?

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.

Electromagnetic induction. a coil of wire contains n turns and has an electrical resistance r. the radius of each turn is a. initially, inside the coil there exists a uniform magnetic field of magnitude b0 parallel to the axis of the coil. the magnetic field is then reduced slowly. the current induced in the coil is i. how long does it take for the magnitude of the uniform field to drop to zero?