A boy and a man carry a uniform bar of length L horizontally so that the boy gets 1/3 of the weight of the bar. If the boy is at one end of the bar, the distance of the man from the other end is L/n. The value of n is ...
Physics · Mixed Chapter
JEE Mains

Question

A boy and a man carry a uniform bar of length L horizontally so that the boy gets 1/3 of the weight of the bar. If the boy is at one end of the bar, the distance of the man from the other end is L/n. The value of n is ...

Physics · Mixed Chapter

G1 Physics · Accepted Answer

Step 1: Let the boy hold the end x=0 and the man support at x=a. The support forces are W/3 and 2W/3, while the weight W acts at x=L/2. Step 2: Taking torques about the boy, (2W/3)a=W(L/2). Thus a=3L/4 from the boy's end. Step 3: The man is L−a=L/4 from the opposite end, equal to L/n. Therefore n=4.