A small rock is thrown straight up with initial speed V0 from the edge of the roof of a building with height H. The rock travels upward
and then downward to the ground at the base of the building. Let
+y be upward, and neglect air resistance. (a) For the rock’s motion from
the roof to the ground, what is the vertical component Vav-y of its average
velocity? Is this quantity positive or negative? Explain. (b) What
does your expression for Vav-y give in the limit that H is zero? Explain.
(c) Show that your result in part (a) agrees with Eq. (2.10).

Hugh D. Young, Roger A. Freedman - University Physics with Modern Physics (15th Edition) Chap. 3 Ex. 73

Answer is in the photo. I can't attach it here, but I've uploaded it to a file hosting. link below! Good Luck!

cutt.ly/XzW3SUN

grav force prop 1/r squared 2r all squared is 4rsquared 1/4rsquared quartered

note: the given question is incomplete.

complete question is given below.

which is an example of kinetic energy?

a. the energy stored in ethanol  

b. a hockey puck sliding across the ice  

c. a compressed spring  

d. a ball sitting at the top of a ramp

solution: the kinetic energy is the energy posses by the virtue of the motion of the object.

in the given options, a, c and d are the example of potential energy because it is the energy posses by the virtue of the rest of the object. but option b has the kinetic energy as the object is in motion.

hence, a hockey puck sliding across the ice   is the apex example of kinetic energy.

so, the option (b) a hockey puck sliding across the ice   is the correct option.