# An application of Dynamics, very difficult, really need help

CWatters
Homework Helper
Gold Member
Can't tell if they included that or not.

Personally I think most of the marks will be for explaining why the mass of the head is important.

So, to summarize, the only resultant points is to make the mass lighter. Or are there other reasons. I can't find the reason and change that needs to be done myself, but i personally i don't think this is enough.

someone mentioned something about the time to take ink. I don't know the physics of printers, but do you think this is a proper reason here. What about the 'electronic' printer as mentioned in the question?

Also, I think I forgot to remind you about the part for the sketch. Have you tried imagining how the graph is - it's simple. Maybe something might be concluded from the shape - it can be said that it has a periodic shape (the same shape repeats itself over and over).

Do you have any last thing to add more before concluding

Strictly speaking from the questions perspective perhaps the force acting to accelerate the printer could be increased, the actual head could be made lighter so it accelerates faster....etc (gosh am I breaking any guidelines!?)
by the way, I've been thinking. Are the magnitudes of the accelerating and retarding forces realistic to be produced in a printer? Or are they too large? Maybe that's oneof the restraints? What do you think? I don't know whether the forces are realistic or not though

if the forces are too great, would it possibly cause the whole printer to move?

is the time the head moves up and down to print already accounted in the question? or maybe this could be a reason for slower printing.

CWatters
Homework Helper
Gold Member
The old fashioned "golf ball" type printers may have worked like this but I don't think modern inkjet printers do. The latter just move the head at a constant speed from one edge of the page to the other. They don't stop the head to print a character they just print dots "on the fly". Those dots can form part of a picture or a character. eg there is nothing special about characters to a modern injet printer.

The old fashioned "golf ball" type printers may have worked like this but I don't think modern inkjet printers do. The latter just move the head at a constant speed from one edge of the page to the other. They don't stop the head to print a character they just print dots "on the fly". Those dots can form part of a picture or a character. eg there is nothing special about characters to a modern injet printer.
so, as a reason, may I say that allowing the head to move at constant speed would be quicker? this involves less mechanical work (I think) - there won't be a need to produce forces that causes accelerations and decelrations - so less friction, less heat, ...

CWatters
Homework Helper
Gold Member
Yes and no. Yes it would make the printer quicker but part iv is really trying to test your knowledge of physics rather than your ability to redesign the printer. They are telling you that the head accelerates, decelerates and stops. I think you are over thinking this.

For example if redesigning the whole printer from a golf ball to an inkjet was a valid answer then it might be equally valid to suggest replacing the entire printer with an industrial printing press capable of printing a few million newspapers a day.

Yes and no. Yes it would make the printer quicker but part iv is really trying to test your knowledge of physics rather than your ability to redesign the printer. They are telling you that the head accelerates, decelerates and stops. I think you are over thinking this.

For example if redesigning the whole printer from a golf ball to an inkjet was a valid answer then it might be equally valid to suggest replacing the entire printer with an industrial printing press capable of printing a few million newspapers a day.
but won't increasing the forces to cause greater accelerations have other drawbacks. How can the force be increased actually?