Aload of 600n is raised by an effort of 2000
by using i meter long crowbar. if the lod is
20cm away from the fulcrum, what is the
efficiency of the crow-bar?

75%

Explanation:

I assume the effort is 200 N, not 2000.

The load is 20 cm from the fulcrum, and the crowbar is 1 m long, so the effort is applied 80 cm from the fulcrum.  So the theoretical load that can be raised is:

20 cm × F = 80 cm × 200 N

F = 800 N

But the actual load is 600 N.  So the efficiency is:

e = 600 N / 800 N

e = 0.75

The efficiency of the crowbar is 75%.

the part of the wave he is travelling on is the crest