Asmall child (m=40kg) is standing on a scale in an elevator. answer the following questions about the forces acting on the boy for each situation.

a. the elevator is moving at a constant velocity of 14m/s. how does the normal force compare to the weight? why?

b. the elevator is accelerating upward at 5m/s^2. how does the normal force compare to the weight? why?

c. the elevator is accelerating down at 5m/s^2. how does the normal force compare to the weight? why?

d. the elevator is accelerating down at 10m/s^2 (equal to the acceleration due to gravity.) what is the normal force? why?

As a car drives with its tires rolling freely without any slippage, the type of friction acting between the tires and the road is 100) a) static friction. b) kinetic friction. c) a combination of static and kinetic friction. d) neither static nor kinetic friction, but some other type of friction. e) it is impossible to tell what type of friction acts in this situation.

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.

Which is an example of an exothermic process?