Questions
A block is dragged on a smooth plane with the help of a rope which moves with a velocity v as shown in the figure. The horizontal velocity of the block is
detailed solution
Correct option is A
Let at any instant of time, the length AB be l, here angle θ and length l vary with time, then using Pythagoras theorem in ∆ABC,x2 + y2 = t2On differentiating both sides w.r.t t, we getor 2xdxdt+2ydydt=2ldldtAs, there is no vertical motion of the block, sodydt=0,dxdt=vx and dldt=v∴ 2xvx = 2lv or vx=lxv or vx=vxl=vsinθSimilar Questions
Two masses of I kg and 5 kg are attached to the ends of a massless string passing over a pulley of negligible weight. The pulley itself is attached to a light spring balance as shown in figure. The masses start moving during this interval; the reading of spring balance will be:
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