STEP III 2009 Q9 Log Out | Topics | Search
Moderators | Register | Edit Profile

Ask NRICH » Onwards and Upwards » STEP III 2009 Q9 « Previous Next »

Author Message
Riversdale
Poster

Post Number: 9
Posted on Tuesday, 22 October, 2013 - 12:18 pm:   

I have solved the first two parts of this question but I do not understand what the official solution says when it says "reversing the motion". Can anyone help? Thank you.
application/pdf
STEP III 2009 Q9.pdf (170.9 k)
kmsquared
Veteran poster

Post Number: 825
Posted on Tuesday, 22 October, 2013 - 03:05 pm:   

Reversing the motion means projecting the particle from Q to P instead of from P to Q.

Kate
Riversdale
Poster

Post Number: 10
Posted on Tuesday, 22 October, 2013 - 03:49 pm:   

I had understood that but could not quite see how it would work. Perhaps I was tired. Is this the only way to do it?
kmsquared
Veteran poster

Post Number: 826
Posted on Tuesday, 22 October, 2013 - 05:48 pm:   

What they seem to be doing is using the fact that the reverse motion is just another example of the same type and substituting the relevant angles into the result they'd obtained (so theta is replaced by -phi and alpha by -alpha). If I get time I'll have more of a look at this question and see if I can think of any other methods.

Kate

Add Your Message Here
Posting is currently disabled in this topic. Contact your discussion moderator for more information.

Topics | Last Day | Last Week | Tree View | Search | Help/Instructions | Program Credits Administration