Question

Please post solutions (step by step) with formulas clearly indicated. Answer is 784N.

A 3.0-m-long rigid beam with a mass of 80 kg is supported at each end. A 60 kg student stands 2.0 m from support 1. How much upward force does support 2 exert on the beam?

Answer 1

As shown from the diagram, let us consider N,N2 are the normal reaction forces at support 1 and support 2 whose directions are vertically upwards Mg is the weight of rigi d beam whose direction is vertically downwards and mg is the weight of student whose direction is vertically downwards If the system in transl ati onal equilibrium , the net force acting on the beam is zero From the newton second law of motion, the net force acting on the beat is If the system in rotational equilibrium , the net torque acting on the beam is zero Torque is the product of force and perpendecular distance from axis of rotation. While cal culating torque use following conventior. Sum of clock wise moments are negative and sum of anticlockwise moments are positive Applying torque equati on axis at the support 1 mg (2.0m)-0 )((32 )-(60kg)(98m/)(20 N2 (3.0m) (80kg)(9.8m/s 2352 (3.0) Solve for N2 -784N