Thank you Ann!

I had the equations and really was closing in on the answer... (stopping for 23 s is what really got me confused) in either case, the displacement for a) is 888 m !
Now I'll try to calculate (b).
Thank you much!

P.S. This is in response to my earlier physics (kinematics) questions.

A more pressing problem for which I have tried over and over again, with no results. I'm able to solve harder problems, but sometimes falter at really easier ones (depressing, I know). Here it is:

section Density and Atomic Mass

A major motor company displays a die-cast model of its first automobile, made from 9.35 kg or iron. To celebrate its hundredth year in business, a worker will recast the model in gold from the original dies. What mass of gold is needed to make the new model?

Look up the density of iron.
mass = volume x density.
You have the mass and density and you calculate volume of iron.

Then look up the density of gold.
mass = volume x density
Solve for mass. You have the volume from the previous calculation.

Gold: Density @ 293 K: 19.32 g/cm3
Atomic Mass: 196.96655 amu

Iron: Atomic Mass: 55.845 Amu
Density: 7.86

Density is mass per unit volume. The average density of an object equals its total mass divided by its total volume. The atomic mass of a chemical element is the mass of an atom at rest.

So for example, a statue made out of gold will be heavier than a statue made of iron because gold has a higher density.
density = mass / volume

watch your signs, density here is given in grams.

To calculate the mass of gold needed to make the new model, we can follow these steps:

1. Look up the density of iron: In the given information, the density of iron is provided as 7.86 g/cm³.

2. Calculate the volume of iron: We have the mass of iron given as 9.35 kg. Since density is equal to mass divided by volume, we can rearrange the formula to calculate the volume: volume = mass / density. Convert the mass to grams (1 kg = 1000 g) and divide it by the density of iron to get the volume in cubic centimeters (cm³).

volume of iron = (mass of iron in grams) / (density of iron)

3. Look up the density of gold: In the given information, the density of gold is provided as 19.32 g/cm³.

4. Calculate the mass of gold: We already have the volume of the iron from the previous calculation. Use the same formula as before, rearranging it to solve for mass:

mass of gold = volume of iron x density of gold

Substitute the values for volume of iron (from step 2) and the density of gold (from step 3) into the formula to find the mass of gold needed.

Remember to keep track of the units and convert if necessary. Make sure to use consistent units throughout the calculations.