Question

A rock weighing 2000N is to be displaced with an effort of magnitude 1200N using a lever. What should be the length of the lever if the possible load arm is only 30cm from the pivot?

Answer 1

let the length of the lever be x

then the other part has a length of 30-x

for lever problems, we take that torque produced by each force should become 0

so, 2000(30-x)=1200(x)

5(30-x)=3(x)

150-5x=3x

8x=150

x=150/8cm=18.75cm

|--------------------o--------------------------------------|

| 30-x x |

2000N. 1200N

you can see this diagram for the concept of zeo torque.