using node js as a shell on a linux system

Run the node commands below and answer the following questions.

 var f = fs.openSync("/tmp/testFile.txt", 'w+'); fs.writeSync(f, "Hello World! ", 20000); fs.closeSync(f); 

1. If you view /tmp/testFile.txt in less, what do you see? Why?
2. What is the logical size of /tmp/testFile.txt? What is the physical size? Obtain both values just using node functions. Explain how each was determined.
3. What system call(s) is the call to fs.writeSync() making? How do you know?