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 Kinematics and Dynamics Kinematics and Dynamics Physics Help Forum Sep 10th 2010, 07:43 AM #1 Junior Member   Join Date: Sep 2010 Posts: 24 General Principles Represent each of the following combinations of units in the correct SI form using an appropriate prefix: d) km*N The answer in the back of the book was mm*N... Why? Then the next question was to evaluate to three significant figures, and to express in SI using the appropriate prefix. (200 kN)^2 Here's my work: [200(10^3) N][200(10^3) N] = 40 000(10^6) N^2 =40.0(10^9) N^2 =40.0 GN^2 the answer says 0.040MN^2   Sep 10th 2010, 11:00 AM #2 Physics Team   Join Date: Jun 2010 Location: Morristown, NJ USA Posts: 2,339 For the first, I'm with you - the proper SI units are meters and newtons, not millimeters and newtons. For the second, remember that the power of 2 applies to both the M and N in MN. Hence 1 MN^2 = 10^6 x 10^6 N^2 = 10^12 N^2. Hence 4 x 10^10 N^2 = 0.04 MN^2. As another example of how this works, consider a square of size 1 KM^2. One square kilometer is not eqal to 1000 square meters, but rather is 1000m x 1000m = 10^6 m^2.  Tags general, principles Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Physics Forum Discussions Thread Thread Starter Forum Replies Last Post Instantonly Special and General Relativity 10 Dec 15th 2016 11:39 PM joey1 Thermodynamics and Fluid Mechanics 0 Mar 8th 2011 10:05 PM jamix Special and General Relativity 1 Sep 21st 2009 01:50 AM DrX Kinematics and Dynamics 1 Mar 14th 2009 03:03 AM MissG Kinematics and Dynamics 4 Mar 3rd 2009 04:50 PM 