SIMPLE physics question..

[Syringer]

This is actually my roommate's hw, and I haven't taken physics in a long time but I had a wondering here..

1. What impulse is needed to stop a 1200-kg car traveling at 20 m/s?

(a) 20 N.s
(b) 1200 N.s
(c) 60 N.s
(d) 24,000 N.s

Now the answer is supposed to be d)..but I don't see how the units work. When you multiply the numbers you get kg*m/s, which is definitely not equivalent to N*s..so how does that work?

 

[TerryMathews]

A Newton is a kilogram * meter/second^2. So a Netwon * second is the same a kilogram * meter * second / second^2 or kg*m/s.

 

[Heisenberg]

kg*m/s^2 is a Newton, so N*s is kg*m/s.

 

[Syringer]

Ooh, duh 🙂

 

[Aken]

Actually, a Newton = (kg*m)/sec^2 so N*s = (kg*m)/s

 

[Darien]

Originally posted by: Aken
Actually, a Newton = (kg*m)/sec^2 so N*s = (kg*m)/s

what's with the ()?

 

[MikeMike]

he doesnt know order of ops obviously 😉

MIKE