Engineers are using computer models to study train collisions to design safer train cars. They start by modeling an elastic collision between two train cars
traveling toware each other. Car 1 is traveling east at 6 m/s and has a mass
of 3,154 kg. Car 2 is traveling west at 23 m/s and has a mass of 8,296 kg.
After the collision, car 1 has a final velocity of 7 m/s west. What is the final
velocity of car 2?
A. 23 m/s west
B. 18 m/s west
O C. 23 m/s east
D. 18 m/s east

An object starts from rest at point f and speeds up continuously as it moves around an oval. a. choose a point about 1/8 th of the way around the oval from point f, and label it point g. draw a vector to represent the velocity of the object at point g. b. determine the change in velocity vector   between points f and g.

Simple machines can a. increase force only b. decrease force only c. increase or decrease force

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?