Saved Bookmarks
| 1. |
A blocklying on a rough horizontal surfaces as show in figure . Its mass is M and it is dispalced through a distanced bya force vec(F )actingat an anglethetawith horizontal. If mu is thecoefficientof friction between a blockandthesurface and mass of block is M . then workdone is ........... |
|
Answer» `W = [ F(sin theta + mu cos theta) - mu Mg] d` FBD of a blockis shown in figure below :  As there is no displacement in Y - DIRECTION , `N + F in theta = Mg = 0 ` ` :. N + F sin theta = Mg` ` :. N = Mg - F sin theta......(i)` Force RESPONSIBLE for displacement in X direction , `F_(1) = F cos theta - f ` where , f = frictional force = `muN` ` = F co theta - mu N ` ` :. F_(1) = F cos theta - mu (Mg - F sin theta)` ( From eq.(1) )`.....(ii)` Now , work `W = F_(1)d` ` = [ F cos theta - mu Mg + Fmu sin theta ] d ` [ From wq. (2)] ` = [ F cos theta +F mu sin theta - mu Mg ] d ` ` :. W = [F(cos theta +mu sin theta) - mu Mg ] d ` |
|