Solve the below problem:
Q: Determine the vertical movement of joint D if the length of member BF is increased by 75 mm. (Hint: Apply a vertical load at joint D, and, using the methods compute the force exerted by member BF on joints B and F. Then apply the method of virtual work for a virtual displacement resulting in the specified increase in length of member BF. The method should be used only for small changes in the lengths of members.)
