5) Reluctant diver Dave is hanging by his fingertips at the high-dive board, a d

Question

5) Reluctant diver Dave is hanging by his fingertips at the high-dive board, a distance of 8m from the water. His friend pries his fingers from the board, so that Dave drops straight down into the water

a) How long does it take Dave to reach the water?

b) how fast is dave going when he hits the surface of the water?

c) sketch graphs for this motion

6) A student throws a set of keys vertically upward to his fraternity brother, who is in a window 4 m above. The brother catches the keys 1.5 s after they are thrown.

a) with what velocity were the keys thrown?

b) what is the velocity of the keys when they were caught?

7) a student stands at the edge of a cliff and throws a stone horizontally over the edge with a speed of 18 m/s. The cliff is 50 m high.

a) how long does it take the stone to reach the ground below the cliff?

b) how far from the base of the cliff does the stone land?

PLEASE SHOW YOUR WORK AND STEPS TO HOW YOU SOLVED IT

Explanation / Answer

5)

s= 0.5gt*t

s=8 g=9.8

we get t=1.27s

v= gt

=12.5 m/s

6)

s= ut -0.5g*t*t

s=4 t=1.5

we get

u =10.016 m/s

7)

sy=0.5g*t*t

sy=50

t=3.19s

sx=18*t

=57.49m

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