A man throw a ball vertically up word with an intial speed 20m/s. What is the maximum height rich by the ball and how long does it take to return to the point it was trow​

u=20 m/s, T=4s

Explanation:

Given final velocity v= 0 m/s and displacement h= 20 m; acceleration due to gravity = 10 m/ s 2

From equation of motion 

v2=u2+2gs−u2=−2(10).20u=20m/s

and time t can be determined by the formula

t=gv−u=−10−20=2s

total time = 2× time of ascend=2×2=4s

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h = 20 m

t = 4 s

Explanation:  

Let g = -10 m/s²

v² = u² + 2as

s = (v² - u²) / 2a

h = (0² - 20²) / (2(-10))

h = 20m

Gravity reduces the initial velocity to zero in a time of

t = v/g = 20/10 = 2 s

It will take just as long to return to the throw height

t = 2(2) = 4s

answer: the rock sample is a sedimentary rock.

explanation:

it is given that:

mass of rock sample, m = 2.7 g

volume of rock sample,

so, density of rock sample will be

since, the density of rock sample is . hence, the rock sample is a sedimentary rock, whose densities varies between .

mass and volume are the answers you are looking for