A lever, 4 metres long, has a fulcrum placed 3 metres from the effort end. What force will be necessary to lift a load of 600 N?

The property of a lever can be given as: 

W1 x D1 = W2 x D2

where, W1 and W2 are weights on the two ends of the lever and D1 and D2 are distances of the weights from the fulcrum, respectively.

Here, effort can be termed as W1 and the load of 600 N as W2. D1 or the distance of the effort arm is 3 m and that of load arm is 1 m (= 4m - 3m), that is D2 = 1 m.

Substituting the values of W2, D1 and D2 in the equation, we get:

W1 x 3 m = 600 N x 1 m

or, W1 = 600/3 N = 200 N.

Thus, an effort of 200 N is able to lift a load of 600 N, if the fulcrum is placed 3 m from the effort arm.

Hope this helps.