Tham khảo tài liệu 'sat ii physics (sn) episode 1 part 7', ngoại ngữ, ngữ pháp tiếng anh phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | A student exerts a force of 50 N on a lever at a distance m from its axis of rotation. The student pulls at an angle that is 60Â above the lever arm. What is the torque experienced by the lever arm Let s plug these values into the first equation we saw for torque This vector has its tail at the axis of rotation and according to the right-hand rule points out of the page. Newton s First Law and Equilibrium Newton s Laws apply to torque just as they apply to force. You will find that solving problems involving torque is made a great deal easier if you re familiar with how to apply Newton s Laws to them. The First Law states If the net torque acting on a rigid object is zero it will rotate with a constant angular velocity. The most significant application of Newton s First Law in this context is with regard to the concept of equilibrium. When the net torque acting on a rigid object is zero and that object is not already rotating it will not begin to rotate. When SAT II Physics tests you on equilibrium it will usually present you with a system where more than one torque is acting upon an object and will tell you that the object is not rotating. That means that the net torque acting on the object is zero so that the sum of all torques acting in the clockwise direction is equal to the sum of all torques acting in the counterclockwise direction. A typical SAT II Physics question will ask you to determine the magnitude of one or more forces acting on a given object that is in equilibrium. EXAMPLE 151 Two masses are balanced on the scale pictured above. If the bar connecting the two masses is horizontal and massless what is the weight of mass m in terms of M Since the scale is not rotating it is in equilibrium and the net torque acting upon it must be zero. In other words the torque exerted by mass M must be equal and opposite to the torque exerted by mass m. Mathematically Because m is three times as far from the axis of rotation as M it applies three times as much .
