UNIVERSITY of PLYMOUTH

 

MECH115: Engineering Science 1

 

Tutorial examples: - Types of Forces                           [Use g = 9.81 m/s² where required]

 

 

  1. A mass of 20 kg is suspended by two light strings making angles of 30º, and 50º to the vertical as shown below. Find the tensions FA and FB in the each of the strings.               [99.6 N, 152.6 N]

 

 

 

 

 

 

 

 

 

 

 


  1. In Question 1 a third string is added at 10º to the vertical on the 50º side and applies a tension force of 35N. Find the forces FA and FB with this added string. [ 76.8 N, 129.8 N]

 

  1. In the simple mechanism shown below the arm AB is pin jointed at A with smooth contact at point B. Find the force at A and B if the mass of the arm AB is 10.5 kg. [51.5 N vert.]

 

 

 

 

 

 

 

 

 

 

 


  1. The ladder shown below is considered to have smooth contact at point A and rough contact at B. Find the force at A and B if the ladder carries a mass of 70 kg 70% up from B.      [128.8 N at 180º, and 700N at 79º]

 

 

 

 

 

 

 

 

 

 

 

 

 

 


  1. The con-rod crank mechanism shown below has a vertical downwards force of 2000N applied to the piston. If AB=17cm, and BC = 8cm, find the force in the connecting rod AB, and the torque applied to the crank at C. Note that there is a side force at A because the piston is constrained to move vertically by the cylinder. The piston cylinder contact is smooth. [ FAB = 2144 N, torque = 162.3 Nm]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


  1. The horizontal beam ABCD below supports forces as shown. Find the moment, and the reaction force on the beam at its point of attachment to the wall at D where it is built in.                        [MD = 52.28 kNm, FD = 72.13 kN at 144.9º ]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


115tut_types_of_forces