Suppose a body is rotating with uniform speed i.e. dv/dt=0(all the drags and frictions are zero) then what will be the direction of torque or will it actually exist?since the only force is acting towards the center and radius and force will make angle of 0 and hence the torque will be zero


closed as off-topic by sammy gerbil, stafusa, Jon Custer, Chris, Mitchell Jan 27 '18 at 4:59

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Homework-like questions should ask about a specific physics concept and show some effort to work through the problem. We want our questions to be useful to the broader community, and to future users. See our meta site for more guidance on how to edit your question to make it better" – stafusa, Jon Custer, Chris
If this question can be reworded to fit the rules in the help center, please edit the question.

  • $\begingroup$ If there's a torque, the body cannot be rotating with uniform speed. $\endgroup$ – Allure Jan 25 '18 at 6:19
  • $\begingroup$ @Allure that's what my doubt was!!!! that in such a case there wont be any torque?what about linear momentum? $\endgroup$ – user181463 Jan 25 '18 at 6:21
  • $\begingroup$ -1 Not clear what your "doubt" is. If you know that there is no torque, what is your difficulty? $\endgroup$ – sammy gerbil Jan 26 '18 at 5:22
  • $\begingroup$ Possible duplicate of Torque direction meaning $\endgroup$ – sammy gerbil Jan 26 '18 at 5:27

Torque is needed to speed up or slow down a spin. Here, the spinning rate is constant, so there will be no net torque. The word "net" here is extremely important. Let's say I apply $2$ $5$N forces in opposite directions. Then, there is torque, but they cancel out.

Now to angular momentum. Linear momentum $p$ is defined by $mv$, mass multiplied by velocity. Assuming the mass is non-zero, there will be momentum. One way to visualise this is to spin a heavy metal ball, using yourself at the pivot. Uponn letting go, the ball will fly. Why? Because there us momentum.

  • $\begingroup$ Sir what would the direction of torque in case the ball is object is rotating in normal situation and there is non zero drag and friction and the ball is gradually slowing down $\endgroup$ – user181463 Jan 25 '18 at 7:51
  • $\begingroup$ @user181463, the torque will be in a direction perpendicular to the plane of rotation. $\endgroup$ – QuIcKmAtHs Jan 25 '18 at 11:41

Not the answer you're looking for? Browse other questions tagged or ask your own question.