page34 Published May 12, 2018 at 1024 × 768 in 5/7-5/11/18 (Work) PhySP18SS6.5.26 Pulling the cart. No work by gravity (mg) because it is 90° to the displacement vector (∆x). THe force of pull does positive work (cosine 0 = 1) and the friction does negative work (cosine 180° = (-1)).