How does refraction cause wave crests to move when the waves approach the shore? a. at right angles to the shore b. about 80 degrees in relation to the shore c. nearly parallel to the shoreline d. about 45 degrees in relation to the shore

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.

Select the correct answer. what does the process of natural selection involve?

Astudent weighing 700 n climbs at constant speed to the top of an 8 m vertical rope in 10 s. the average power expended by the student to overcome gravity is most nearly