A 6m*4m*2m block weighing 1500kg is resting with its 6m*4m file on the ground. The work done in making it stand with its 2m*4m face on the ground is
Consider that the entire block comprises of two blocks, I and II whose dimensions you can see in the picture above. Notice that in bringing the entire system from the first configuration to the second, as described in the question, block II does not change its position at all. The entire work done is done to pick up block I and placing it on the top of block II. In proper terms, total work done = work done in raising block I from h=0 to h=2m (see the image).
Now, the block is of uniform density. Mass is directly proportional to volume. MI + MII = 1500kg
volumeI = 4*4*2 = 32m3 and volumeII = 2*2*4 = 16kg. Hence, MI = (32/48)*1500 = 1000kg
Hence work done = F.d = MI*g*h = 1000*9.81*2 = 19,620J
Or, with g= 10m/s2, W = 1000*10*2 = 20,000J