47. A compact car, mass 875 kg, moving south at 15 m/s, is struck by a full-sized car, mass 1584 kg, moving east at 12 m/s. The two cars stick together, and momentum is conserved in the collision. a. Sketch the situation, assigning coordinate
axes and identifying "before" and "after."
b. Find the direction and speed of the wreck
immediately after the collision, remembering that momentum is a vector quantity.
c. The wreck skids along the ground and comes to a stop. The coefficient of kinetic friction while the wreck is skidding is 0.55. Assume
that the acceleration is constant. How far
does the wreck skid?
40
7

During physical science, ms. greene challenged her students to produce an energy transformation. james and jill wrapped a 4-inch nail with a coil of fifty turns of wire. they connected one end of the coil to one terminal of a knife switch. they connected the other terminal of the knife switch to the battery. finally, they connected the end of the coil to the other terminal of the battery. james held the tip of a 1-inch nail near the flat end of the 4-inch nail. jill closed the knife switch quickly and then opened it. the 1-inch nail was pulled toward the 4-inch nail. what is the best explanation of why the nail moved? a) electrical energy was converted to mechanical energy in the 1-inch nail. b) the 4-inch nail became an electromagnet and the magnetic force attracted the 1-inch nail. c) the electric current in the 4-inch nail was converted to mechanical energy in the 1-inch nail. d) the 4-inch nail had a positive charge and the 1-inch nail had a negative charge. opposites attracted.

If a substance is in the gas phase, which of qualities of the gas will stay constant? a: volume b: mass c: shape d: position of particles

What is the average speed of a car that travels 40 mph for 1 hour and 60 mph in another hour?