Item 13 The two ropes seen in the figureFigure 1 are used to

Item 13

The two ropes seen in the figure(Figure 1) are used to lower a 255 kg piano 5.10 m from a second-story window to the ground.

Part A How much work is done by each of the three forces? Enter your answers numerically separated by commas. WG, W1, W2 =

Solution

Mass of piano m = 255 kg

Height h = 5.1 m

Weight of piano WG = mg = 255x9.8

                                    = 2499 N

                                    ~ 2500 N

Work done by weight is =WG x h

                                   = 2500 N x 5.1 m

                                   = 12750 J

Work done by tension T1 is W1= - T1 sin 60 x h    Since T1 sin 60 and h are opposite to each other.

                                              = -1830 sin 60 x5.1

                                              = -8082.6 J

Work done by tension T2 is W2= - T2 sin 45 x h    Since T1 sin 60 and h are opposite to each other.

                                              = -1295 sin 45 x5.1

                                              = -4670 J