1.What is the unit for kinetic energy?

2.A collision in which kinetic energy is conserved is calledwhat?

3. It takes no work to hold a cheerleader in the air, as shownhere. If no work is done by the cheerleaders, why do theyeventually tire?

	A.The concept of work, as it apples in physics, does not applyto any process that involves people.
	B.Their bodies expend chemical energy as their musclesfunction; this is \"hard work,\" but not the same kind of work thatmoves a mass over a distance.
	C.The arrangement is unstable and they can easily fallover.
	D.The cheerleaders at the greater height have more potentialenergy.
	E. Maintaining the same position for a long time is boring. 4.If the orbit is elliptical, rather than circular, what can besaid about the work done by the Sun on Earth? a.If the orbit is elliptical, work is done to speed up or toslow down Earth, depending on its location in orbit. b.Whether the orbit is circular or elliptical, work must be doneto propel Earth around the Sun.   c The work the Sun does on Earth causes the tides. d.The work the Sun does on Earth accounts for Earth's changes ofseason. E. It does not matter whether the orbit is circular orelliptical, no work is done. 5.In a rollercoaster, provided losses of thermal energy becauseof friction can be neglected, which of the following is true? A.The kinetic energy decreases as the car moves to the top ofthe slope. B.The rollercoaster moves at constant speed as its height abovethe ground increases.     C. The gravitational potential energy decreases as the car movesto the top of the slope. D.The mechanical energy decreases as the car moves to the top ofthe slope. E.The mechanical energy increases as the car moves to the top ofthe slope.