i just had this question and i totally guessed. it was 2.2.
Answer:
Approximately 
if that athlete jumped up at 
. (Assuming that 
.)
Explanation:
The momentum 
of an object is the product of its mass 
and its velocity 
. That is: 
.
Before the jump, the speed of the athlete and the earth would be zero (relative to each other.) That is: 
and 
. Therefore:
and 
.
Assume that there is no force from outside of the earth (and the athlete) acting on the two. Momentum should be conserved at the instant that the athlete jumped up from the earth.
Before the jump, the sum of the momentum of the athlete and the earth was zero. Because momentum is conserved, the sum of the momentum of the two objects after the jump should also be zero. That is:
.
Therefore:
.
.
Rewrite this equation to find an expression for 
, the speed of the earth after the jump:
.
The mass of the athlete needs to be calculated from the weight of this athlete. Assume that the gravitational field strength is 
.
.
Calculate using 
and 
values from the question:
.
The negative sign suggests that the earth would move downwards after the jump. The speed of the motion would be approximately .
Watersheds provide many of us with our drinking water supply, plus recreational opportunities and aesthetic beauty. Watersheds are areas from which water runs into a public water supply. Thus, much of the water you drink from a public source has passed through a watershed. Because of this, it's important that care be taken to minimize any contaminents that may find their way into a public water supply. A small example of a watershed would be the hills around a reservoir. A larger example would be the portions of Pennsylvania, New York, Virginia, Maryland, Delaware and Washington DC that are designated Chesapeake Bay watershed.
Answer: "People will say the length of a day is determined by just the rotation rate of a planet, but that isn’t entirely true. The orbit around its sun also factors in. What we define as a day is the time between when the Sun is highest in the sky until the next time the Sun is at the highest point in the sky. This isn’t just the time it takes the Earth to rotate once on its axis, though. This is because, as the Earth is rotating, it’s also moving relative to the Sun"
The answer is A I had this question. Before
