# Homework Help: Quick Question about the acceleration formula

1. Apr 17, 2006

### oooo

When you use the formula a=F*k, what are the units of k (such as N, m, s, that kind of thing). I need to know for a problem I have to do for homework, so if you could clear it up for me it would help!

2. Apr 17, 2006

### Pseudo Statistic

Think about it this way, a is ms^-2, and F is N. By the definition of 1 N, 1 N = 1 kg ms^-2
So,
ms^-2 = (X)* kg ms^-2
Where X is the unknown unit of k.......
In this case, treat each unit as an algebraic quantity, re-arrange for X and you'll know what the units are... (Dimensional analysis...)

You may ask why I left the numbers out..... Well, even if you have 3 N on one side with a being 1 ms^-2 on the other side, we really don't care what the value of k IS in this case, just what kind of a unit it represents...
So yeah.

3. Apr 17, 2006

### oooo

Well, all that I know is that in Newton's Second Law, F=m*a, which is the same as a=F/m. Then, looking at a similar formula using k, I see that a=k/m. Thus I thought that k=F and thus k was in units of Newtons. But, for some reason I was wrong. Am I on the right track???

4. Apr 17, 2006

### Pseudo Statistic

Actually, I think you're referring to "Hooke's Law".
In that case, F = kx... = ma, or a = kx/m... not k/m....
{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9347432255744934, "perplexity": 1099.4534473568397}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-26/segments/1529267868135.87/warc/CC-MAIN-20180625150537-20180625170537-00171.warc.gz"}