The scrapyard uses a big electromagnet to move around large metal objects such as cars and appliances. If the operator needed to drop a car to a new space, what would he need to do for this to happen?
A) The magnetic field cannot be turned off.
B) The magnetic field can be turned off by switching off the current.
C) The magnetic field can be reversed by switching the poles of the core.
D) The magnetic field can be decreased by placing it in proximity to an opposite pole.

Aleaky 10-kg bucket is lifted from the ground to a height of 15 m at a constant speed with a rope that weighs 0.7 kg/m. initially the bucket contains 45 kg of water, but the water leaks at a constant rate and finishes draining just as the bucket reaches the 15-m level. find the work done. (use 9.8 m/s2 for g.) show how to approximate the required work by a riemann sum. (let x be the height in meters above the ground. enter xi* as xi.) lim n → ∞ n (9.8)(45−3 xi) i = 1 δx express the work as an integral. 0 dx evaluate the integral. (round your answer to the nearest integer.) j