A monkey is tossing fruit from a tree and trying to hit a rock below. The monkey
ID: 1361917 • Letter: A
Question
A monkey is tossing fruit from a tree and trying to hit a rock below. The monkey tosses the fruit either straight up or straight down. On one toss, the fruit is in free fall for 4.5 seconds and hits the rock with a speed of 30.9m/s.
(a) Which way is the fruit going when it hits the rock?
(b) How fast and in what direction did the monkey throw the fruit?
(c)When was the fruit at its maximum height?
(d)What was the fruit’s maximum height?
(e)How much work did the Earth do to the fruit, in terms of its inertia m, g and any necessary numbers you found or constants used in the problem. If you feel you are missing a number, make up a symbol, define it and use it. •if you consider just the fruit as your system? •if you consider the Earth-fruit as your system?
Explanation / Answer
a)
the fruit travels in down direction
b)
Using the equation
Vf = Vi + g t
- 30.9 = Vi - 9.8 (4.5)
Vi = 13.2 m/s
in up direction
c)
Vf = 0 = final velocity at max. height
using the equation
Vf = Vi + g t
0 = 13.2 - 9.8 t
t = 1.35 sec
d)
using the equation :
d = Vi t + (0.5) g t2
d = 13.2 x 1.35 - 4.9 (1.35)2
d = 8.89 m