Question

4. Consider a circular object that is free to rotate about its central axis. The object is sitting horizontally on ice, so that ction is negligible. (Think of a hockey rotating, or more precisely to change its rate of rotation? Is it a net force, which is the cause of changes in linear motion, or is it something else? puck.) An i is, what exactly causes such an object to start mportant ues ion The diagrams below show such an object with various forces applied to it. In each case, will the object rotate? Will it accelerate linearly? Or perhaps it will do both, or neither. In each case, carefully answer the following three questions: (i) Is there a net force on the object? (ii) Is there a net torque on the object? (iii) What is the resulting motion of the object, assuming that the forces shown are the only forces acting upon it. (Remember, the object is horizontal.) r analysis of the above diagrams, what can you conclude about the cause of rotational (or angular) acceleration?

Answer 1

If there is a net force then there linear acceleration. If there is net torque then it will rotate. If both, then both will take place and if neither net force nor net torque is there, then neither will occur.

(a)

i) Yes

ii) No

iii) Linear acceleration

(b)

i) No

ii) Yes

iii) Rotation

(c)

i) Yes

ii) No

iii) Linear acceleration

(d)

i) Yes

ii) Yes

iii) Both linear acceleration and rotation

(e)

i) No

ii) No

iii) No motion.

f) Cause of rotation is net torque acting on the object.