College Physics with MasteringPhysics 7th Edition by Jerry Wilson,Anthony Buffa,Bo Lou

تمرين 127

A person has a choice while trying to push a crate across a horizontal pad of concrete: push it at a downward angle of 30°, or pull it at an upward angle of 30°. (a) Which choice is most likely to require less force on the part of the person: (1) pushing at a downward angle; (2) pulling at the same angle, but upward; or (3) pushing or pulling shouldn't matter (b) If the crate has a mass of 50.0 kg and the coefficient of kinetic friction between it and the concrete is 0.750, calculate the required force to move it across the concrete at a steady speed for both situations.