Jump to content

Dragster problem


EvoN1020v
 Share

Recommended Posts

Frictionless front wheels and 2 back wheels with [math]F_b[/math] applied at each.

 

I thought that would be enough of a hint. A quote from the question

 

"and the normal reaction at EACH of the TWO wheels at A and B respectively"

 

I make that four wheels. Your answer spreads a normal force equalling the force of gravity in the opposite direction over two wheels - one at the front and one at the back

Link to comment
Share on other sites

I thought that would be enough of a hint. A quote from the question

 

"and the normal reaction at EACH of the TWO wheels at A and B respectively"

 

I make that four wheels. Your answer spreads a normal force equalling the force of gravity in the opposite direction over two wheels - one at the front and one at the back

Yeah that was where I got struck on - the wording of the question. I did my calculations and I hope this is right: [math]F_B=4,500N, B_y=5,576.8N, and A_y=1,780.7N[/math]. If you want the TOTAL reactions at each A and B then just multiply Ay and By by two.

Link to comment
Share on other sites

Yeah that was where I got struck on - the wording of the question. I did my calculations and I hope this is right: [math]F_B=4,500N, B_y=5,576.8N, and A_y=1,780.7N[/math]. If you want the TOTAL reactions at each A and B then just multiply Ay and By by two.

 

I don't like it; from a quick glom it looks as if you have torque around the CoM - which is wrong.

Link to comment
Share on other sites

Yeah - but I made the same mistake EvoN made - after pointing he was using only one set of wheels I used only one wheels worth of thrust

Here's a screenshot of calculations that I did yesterday. I put down 2 Fb for friction force at both back wheels and 2 normal reactions at each A and B. Is it good?

post-2249-0-30059800-1475009457_thumb.jpeg

Link to comment
Share on other sites

Here's a screenshot of calculations that I did yesterday. I put down 2 Fb for friction force at both back wheels and 2 normal reactions at each A and B. Is it good?

If it was a test or assignment it would depend on who is marking it. Just my opinion, but it is better to circle the answers to the questions than double them, even if it somewhat makes sense to do so by adding "at A" and "at B". It would be even more important if a mistake was made and you did not get the right answers.

Link to comment
Share on other sites

If it was a test or assignment it would depend on who is marking it. Just my opinion, but it is better to circle the answers to the questions than double them, even if it somewhat makes sense to do so by adding "at A" and "at B". It would be even more important if a mistake was made and you did not get the right answers.

Yeah either way I'm confident with my calculations. I only care about the "process" not the answer. Thanks guys!

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.