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joshptyltd

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## Homework Statement

A hot-air balloon is ascending at the rate of 10 m/s and is 95 m above the ground when a package is dropped over the side. (a) How long does the package take to reach the ground? (b) With what speed does it hit the ground?

## Homework Equations

vf^2=vi^2+2*a*d

## The Attempt at a Solution

using 0 for vi^2, -9.8 for a, and 95 for d. I got -43.25 m/s. I put this into Wiley Plus and it says it's wrong. I only have 1 more attempt. So I'm thinking, maybe the initial velocity of the object 10 m/s, rather than 0. This has me a little confused.

And for the time taken , i got 3.259s using (v-u)/d

[c]1.

On a dry road, a car with good tires may be able to brake with a constant deceleration of 3.03 m/s2. (a) How long does such a car, initially traveling at 25.0 m/s, take to stop? (b) How far does it travel in this time?

[c]2

t= (x-x0)/(v0+1/2a)

[c]3

I used 103.125 as x, 0 for x0, 25 for v0, and -3.03 as a. But it says my answer is wrong. I got 4.391secs.

I got part b right.

d[1]

Iron has a mass of 7.87 g per cubic centimeter of volume, and the mass of an iron atom is 9.27 × 10-26 kg. If you simplify and treat each atom as a cube, (a) what is the average volume (in cubic meters) required for each iron atom and (b) what is the distance (in meters) between the centers of adjacent atoms?

d[2]

For part a, I divided 7.87*10 to the 3 by 9.27*10 to the negative 26. I got the answer right. I don't know where to start with b.

Thanks very much. :)

PS: Also, it's due in around 6 hours. I'm an idiot for leaving it too late.

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