A large tank contains a liquid of density 1100kg/cubic meters. A small wooden block of uniform density is held suspended by a cord near the bottom of the tank.

When the cord is cut, the block is observed to rise vertically, without rotating a distance of 15.0 meters in 4.70 seconds. From this information deduce the density of the wood

So what do YOU think.
We're happy to help, but we will NOT do all of the work for you.
Show use what you have done so far.

But I didn't get an answer

The working is more important than the answer

The working is more important than the answer

Please show me theworkin then

That's what I was asking you for..
After all if you have no idea how to work this out then you need to refer to your text books and what you have recently been doing in class.

Here's a hint to get you started - there's a force acting upwarrd due to the buoyancy of the wood, and there's a force actig down due to its weight. The result of these two forces is upward movement at some acceleration that you can calculate from the data you've been given. The only "trick" is to know that the upward force due to buoyancy is equal to the difference between the weight of the wood block and the weight of the liquid of the same volume as the block.

One other thing: though you don't say it explicitly I think you can assume that any drag on the motion of the block as it rises due to viscosity of the liquid can be ignored.