https://www.khanacademy.org/science/ap-physics-c-mechanics/x077f5683c1428fac:force-and-translational-dynamics/x077f5683c1428fac:friction-and-resistive-forces/a/what-is-friction 2026-05-01T14:10:52.97313295Z Learn and try: Friction Learn how to measure and model the force of friction. Distinguish between kinetic and static friction. article https://www.khanacademy.org/science/ap-physics-c-mechanics/x077f5683c1428fac:force-and-translational-dynamics/x077f5683c1428fac:friction-and-resistive-forces/e/friction-ap1 2026-06-19T17:56:42.733541135Z Friction Practice analyzing scenarios involving static and kinetic friction. exercise https://www.khanacademy.org/science/ap-physics-c-mechanics/x077f5683c1428fac:force-and-translational-dynamics/x077f5683c1428fac:friction-and-resistive-forces/v/motion-as-a-function-of-time-friction-example 2025-12-22T19:58:53.002174583Z Motion as a function of time: Friction example Applying Newton’s second law to a moving object experiencing kinetic friction results in a differential equation for velocity. The differential equation can be solved to find the object’s velocity as a function of time. The velocity function can then be used to find the object’s acceleration and position as functions of time through differentiation and integration, respectively. The force is constant while the object moves, so we find the velocity function is linear and the position function is quadratic. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/bc9b17e9-824e-4e83-a5d0-443d43b47747_1280_720_base.png Motion as a function of time: Friction example Applying Newton’s second law to a moving object experiencing kinetic friction results in a differential equation for velocity. The differential equation can be solved to find the object’s velocity as a function of time. The velocity function can then be used to find the object’s acceleration and position as functions of time through differentiation and integration, respectively. The force is constant while the object moves, so we find the velocity function is linear and the position function is quadratic. https://cdn.kastatic.org/ka-youtube-converted/T3UBiY4sHKA.mp4/T3UBiY4sHKA.mp4 769 Friction and resistive forces https://www.khanacademy.org/science/ap-physics-c-mechanics/x077f5683c1428fac:force-and-translational-dynamics/x077f5683c1428fac:friction-and-resistive-forces/v/motion-as-a-function-of-time-resistive-force-example-part-1 2025-12-22T19:58:53.002174583Z Motion as a function of time: Resistive force example (part 1) A resistive (drag) force is a velocity-dependent force which acts opposite the direction of an object’s velocity. Applying Newton’s second law to an object experiencing a resistive force results in a differential equation for velocity. Using the method of separation of variables, the velocity can be determined by integrating over the proper limits of integration. Terminal velocity is the maximum speed achieved by an object moving under the influence of a constant force and a resistive force that are exerted on the object in opposite directions. Terminal velocity is reached when the net force exerted on the object is zero. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/86215360-1b42-4ae2-808a-d8456cceafbf_1280_720_base.png Motion as a function of time: Resistive force example (part 1) A resistive (drag) force is a velocity-dependent force which acts opposite the direction of an object’s velocity. Applying Newton’s second law to an object experiencing a resistive force results in a differential equation for velocity. Using the method of separation of variables, the velocity can be determined by integrating over the proper limits of integration. Terminal velocity is the maximum speed achieved by an object moving under the influence of a constant force and a resistive force that are exerted on the object in opposite directions. Terminal velocity is reached when the net force exerted on the object is zero. https://cdn.kastatic.org/ka-youtube-converted/d5BNFRylOZE.mp4/d5BNFRylOZE.mp4 900 Friction and resistive forces https://www.khanacademy.org/science/ap-physics-c-mechanics/x077f5683c1428fac:force-and-translational-dynamics/x077f5683c1428fac:friction-and-resistive-forces/v/motion-as-a-function-of-time-resistive-force-example-part-2 2025-12-22T19:58:53.002174583Z Motion as a function of time: Resistive force example (part 2) A resistive (drag) force is a velocity-dependent force which acts opposite the direction of an object’s velocity. Applying Newton’s second law to an object experiencing a resistive force results in a differential equation for velocity. The differential equation can be solved to find the object’s velocity as a function of time. The velocity function can then be used to find the object’s acceleration and position as functions of time through differentiation and integration, respectively. The functions are exponential and have asymptotes that are determined by the initial conditions and the forces exerted on the object. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/10be96b8-9c38-42f0-98b9-b1cb7be0081e_1280_720_base.png Motion as a function of time: Resistive force example (part 2) A resistive (drag) force is a velocity-dependent force which acts opposite the direction of an object’s velocity. Applying Newton’s second law to an object experiencing a resistive force results in a differential equation for velocity. The differential equation can be solved to find the object’s velocity as a function of time. The velocity function can then be used to find the object’s acceleration and position as functions of time through differentiation and integration, respectively. The functions are exponential and have asymptotes that are determined by the initial conditions and the forces exerted on the object. https://cdn.kastatic.org/ka-youtube-converted/F5Tg46DVWzo.mp4/F5Tg46DVWzo.mp4 730 Friction and resistive forces https://www.khanacademy.org/science/ap-physics-c-mechanics/x077f5683c1428fac:force-and-translational-dynamics/x077f5683c1428fac:friction-and-resistive-forces/e/resistive-forces 2026-06-16T19:28:41.750798603Z Resistive forces Apply your knowledge of resistive forces in this set of free practice questions. Emily Cizmas exercise