Block moving on a circular track-Work energy Circular Motion problem

[ehild]

echild...i perfectly understand the first method...regarding second method...work done by pulling force is FL which is work done on the system...but system comprises of block and string wherein string is massless so its mechanical energy is zero .Total energy of system is equal to total energy of block ...?am i right ...this means if the string were having mass then we would not be able to apply the second method?because here

When you calculate the speed of the block, do not forget the work of gravity. The change of KE is equal to the work of all forces...

ehild

 

[Tanya Sharma]

echild ...thanks a ton... what an explanation...u have made physics enjoyable...i m very very grateful

thanks to Doc Al ...u were correct but the language confused me...

 

[ehild]

Thanks Tania. You are really very kind. I am pleased that you feel Physics enjoyable. It is.
Remember Doc Al sentence: The work done on a system by a force is

The force applied times the displacement of the point of application of that force

. It is very important.

ehild

 

[Doc Al]

Well, have you got that coffee since then? You totally confused me, so as I deleted my post and had to rewrite it when the example of the simple pulley occurred to me. And I was surprised by the result of the integral method. (I blame it to the hot damp weather here. It is difficult to think.)

ehild

Sorry about that, ehild! And yes, I've been drinking a lot of coffee since then.

 

[ehild]

Sorry about that, ehild! And yes, I've been drinking a lot of coffee since then.

Take care, too much coffee is bad to hearth. (I also had a coffee since then. )

ehild