(Assume no friction in this problem.) A 85 kg skateboarder coasts down a hill that is 5m tall. At the bottom of the hill, he has a choice of two ramps. The first is 7m tall with a slope of 15 degrees and
the second is 12m tall with a slope of 10 degrees. He believes he will coast to a higher point on the
second hill since he climbs quicker on a steeper hill. Is he right? Why or why not?

Which compound is held together by the electrostatic force between two ions? a. co2 b. cci4 c. h2s d. mgf2

Astudent throws a water balloon with speed v0 from a height h = 1.76 m at an angle θ = 21° above the horizontal toward a target on the ground. the target is located a horizontal distance d = 9.5 m from the student’s feet. assume that the balloon moves without air resistance. use a cartesian coordinate system with the origin at the balloon's initial position. (a) what is the position vector, rtarge t, that originates from the balloon's original position and terminates at the target? put this in terms of h and d, and represent it as a vector using i and j. (b) in terms of the variables in the problem, determine the time, t, after the launch it takes the balloon to reach the target. your answer should not include h. (c) create an expression for the balloon's vertical position as a function of time, y(t), in terms of t, vo, g, and θ. (d) determine the magnitude of the balloon's initial velocity, v0, in meters per second, by eliminating t from the previous two expressions.

Does heating a metal wire increase or decrease its electrical resistance? why?