# Converting Slugs to Newtons

1. Oct 7, 2004

### Mitchell

I am working a Physics problem where the mass is given as 20 slugs. To obtain Newtons can I just multiply 20 slugs x (14.59 kg/1 slug) x 9.80 m/s^2 = 2859.64N?

2. Oct 7, 2004

### Gokul43201

Staff Emeritus
Yes, that's right !

Make sure it is the mass that is described as 20 slugs, because slug is also a unit of force itself !!

3. Oct 7, 2004

### Staff: Mentor

Careful. Since a slug is a unit of mass, not force, you can't "convert" slugs to newtons. But if you are trying to find the weight of a 20 slug mass, then you are fine. (Your conversion of slugs to kilograms is correct.)

4. Oct 7, 2004

### Mitchell

So is the mass of a slug 1lb.? And if so, to obtain (mass x gravity) in the U.S. Customary System would it just be 1 x 32 ft/sec^2 to obtain its weight?

5. Oct 7, 2004

### Staff: Mentor

In the "British Engineering" System, the unit of mass is the slug and the unit of force is the pound. (Yes, sometimes the pound is also used as a unit of mass--but in my opinion, this is a bad idea in a physics course. 1 pound mass = 0.45359237 kg) The weight of a 1 slug mass is given by W=mg = (1 slug) (32 ft/s^2) = 32 pounds (approximately) as you noted.

6. Oct 7, 2004

### Mitchell

Thank you. It's very confusing but your last explination worked and resulted in a correct answer. I hate it when I get the Free body diagrams right, setting up the 2 equations with two unknowns right, and missing the correct answer due to conversion errors. Again...thank you for your help.