You are climbing in the high sierra where you suddenly find yourself at the edge of a fog-shrouded cliff. to find the height of this cliff, you drop a rock from the top and 8.80 s later hear the sound of it hitting the ground at the foot of the cliff.

One day, after pulling down your window shade, you notice that sunlight is passing through a pinhole in the shade and making a small patch of light on the far wall. you see that the patch of light seems to be a circular diffraction pattern. it appears that the central maximum is about 1 cm across and you estimate that the distance from the window shade to the wall is about 3 m. what is (a) the average wavelength of sunlight? (b) the diameter of the pinhole?

Will you chech and finish these for me, because i am stumped with them.

While carrying a heavy box up the stairs,you set the box on a step and rest. then you pick up the box and carry it to the top of the stairs. describe these actions in terms of balanced and unbalanced forces acting on the box.