Why and how hiccups arise.is it necessary for us,if yes then how and why it's necessary to us.
Friction is necessary evil why?
Explain why friction is necessary to make the disc in Fig. 7.41 roll in the direction indicated.
(a) Give the direction of frictional force at B, and the sense of frictional torque, before perfect rolling begins.
(b) What is the force of friction after perfect rolling begins?
Why is friction considered a necessary evil