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1. The problem statement, all variables and given/known data

A hoist is lifting a naturalist to the top of a cliff at 2.03 m/s vertically. The naturalist suddenly realizes she has left her pet rock behind. A friend picks it up and tosses it straight upward. If the naturalist is 2.50 m above her friend, what is the minimum initial speed the pet rock must have to reach the naturalist?

(consider gravitational acceleration as 10ms^{-2}& air resistance negligible)

2. Relevant equations

s = ut + ½ at^{2}

v= u + at

v^{2}= u^{2}+ 2as

Hereuis initial velocity &vis final velocity

3. The attempt at a solution

The information of problem as follows

.........The hoist........................pet rock

u .........2.03................................. ?

v.........2.03................................. ?

s .........2.5 +x........................2.5 +x

t ...........?................................. ?

a.........non.................................-10

the both time & displacement should be equal

So the displacement of hoist

2.5 + x

The get minimum initial velocity the final velocity should be 0.

v = u + at

0 = u - 10t

t = u/10

the u is equal to

v^{2}= u^{2}+ 2as

u^{2}= 20(2.5+x)

the displacement is equal to

s = ut + ½ at^{2}

2.5 + x = ut - 5t^{2}

from here i don't have any idea, please help me.

What is the time of hoist when pet rock reach

2.5 + x = 2.03t

t = (2.5 + x)/2.03

or

x = 2.03t

t = x/2.03

which one i should take

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# Homework Help: Free fall, problem,

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