Which statement is true?

the earth's moon is thought to have formed when a mars-sized planet collided with earth during its final stages of planetary accretion.
without the earth's moon, life on earth would not be possible.
the earth's moon is the smallest moon relative to its host planet.
the earth's moon is the same size as the earth.

Aplayground slide is 8.80 ft long and makes an angle of 25.0° with the horizontal. a 63.0-kg child, initially at the top, slides all the way down to the bottom of the slide. (a) choosing the bottom of the slide as the reference configuration, what is the system's potential energy when the child is at the top and at the bottom of the slide? what is the change in potential energy as the child slides from the top to the bottom of the slide? (include the sign of the value in your answer.)