A bucket of mass M = 5.47 kg is attached to a second bucket of mass m = 3:52 kg by an ideal string. The string is hung over an ideal pulley. Mass M is started with an intial downward speed of 2.13m/s. What then is the speed of mass (M) after it has moved 2.47m? The answers is 3.88 however, I keep getting 3.24. Can anyone help I am not sure how I am off. Thanks

Question

A bucket of mass M = 5.47 kg is attached to a second bucket of mass m = 3:52 kg by an ideal string. The string is hung over an ideal pulley. Mass M is started with an intial downward speed of 2.13m/s. What then is the speed of mass (M) after it has moved 2.47m?  The answers is 3.88 however, I keep getting 3.24.  Can anyone help I am not sure how I am off.  Thanks

bobpursley · Answer

I assume it is an Atwood machine. accelerating force: (5.47-3.52)g F=ma or a=F/m=1.95g/m=1.95*9.8/8.99=2.12 vf^2=vi^2+2ad Vf^2=0+2*2.12* 2.47 I get your answer.

Sarah · Answer

Thanks that really helped. You get 3.88 if for vi you plug in the 2.13. Now I got it thanks