1) acceleration of a point in contact with groung is zero,
2) The speed of some of the point(s) is(are) zero.
3) Friction force may or may not be zero.
4) workdone by friction may or may not be zero.
Which of the following is correct?
a) 2 , 3
b) 1 , 2
c) 3,4
d) 1,4