An object with a mass of # 25 kg# is lying still on a surface and is compressing a horizontal spring by #5/2 m#. If the spring's constant is # 4 (kg)/s^2#, what is the minimum value of the surface's coefficient of static friction?

2 Answers
Jan 21, 2016

Answer:

I found #0.04#

Explanation:

Have a look:
enter image source here

Jan 21, 2016

Answer:

# mu = (kx)/(mg)#
#mu = 2/49#
# mu ~~ .04 #

enter image source here

Explanation:

Take a look at the figure ignore d(t) we will not need it
Now put free body diagram we will have the following equations

  1. #W = N#
  2. #F_k =kx = F_f #
    Where,
    #W = mg#
    N = Normal force;
    #F_k# = spring force
    #F_f# = frictional force
    now #F_f = muN#
    But #N = mg#
    So, #mumg = kx# substitute and get
    # mu = (kx)/(mg)#
    #mu = 2/49#