# Physics in Calc

1. Nov 27, 2003

### gigi9

Someone plz help me how to do these problems below. Thanks a lot for your help.
1) On the surface of the moon the acceleration due to gravity is approximately 1/6 the sun at the surface of the earth, and on the surface of the sun it is approximately 29 times as great as at the surface of the earth. If a person on earth can jump with enough initial velocity to rise 5ft, how high wil the same initail velocity carry that person (a) on the moon? (b) on the sun?
***I had s= -16t^2+ int. v*t+ int. s
s=5, int.s=0...what should I find, how do I do this problem?

2) Find the natural length of a spring if the work done in stretching it from a length of 2ft to the lenght of 3ft is one-fourth the work done in stretching it from 3ft to 5ft.
**Force=k*x,k is a constants, what I did was the force of stretching from 2ft-3ft is F1=k*1ft, F2=4*F1...not sure if I started out right...plz show me how to do it.

3) A great conical mound of height h is built by the slaves of an oriental monarch, to commemorate a victory over the barbarians. If the slaves simply heap up uniform material found at ground level, and if the total weight of the finished mound is M, show that the work they do is 1/2h*M
**I'm totally stuck w/ this problem..what integral should i use???

2. Nov 27, 2003

### HallsofIvy

Staff Emeritus
I would suggest that you post this to the homework forum and show as much as you can about what you have already done and what you do understand about each problem.

For example you say "***I had s= -16t^2+ int. v*t+ int. s
s=5, int.s=0". What do each of those letters and numbers stand for? In particular, where did that "-16" come from?

3. Nov 27, 2003

### Ambitwistor

gigi9 already posted this question to the College Help forum two days ago, and I posted an answer. Perhaps it wasn't satisfactory.

4. Nov 27, 2003

### PrudensOptimus

If you really want a good reply,

Make sure you state your problems clearer by using TEX notation, or some other "Reading friendly" notations.

5. Nov 27, 2003

### Hurkyl

Staff Emeritus