I'm struggling to get the correct answer on the attached problem, the answer I keep getting is 4.4 (2s.f) for which it tells me the sign at some point during my calculation is incorrect even if I try to reverse engineer the problem (use different values of s till I get the correct value for t) I still get 4.4. I'm not sure if my understanding of the question is wrong or my calculations are wrong. If it would help I can post my answers to the previous parts. (part D) https://isaacphysics.org/questions/running_return
I'm struggling to get the correct answer on the attached problem, the answer I keep getting is 4.4 (2s.f) for which it tells me the sign at some point during my calculation is incorrect even if I try to reverse engineer the problem (use different values of s till I get the correct value for t) I still get 4.4. I'm not sure if my understanding of the question is wrong or my calculations are wrong. If it would help I can post my answers to the previous parts.
Which part of the problem do you have issue? Be specific, please. Post the working to the part of the question that you get it wrong.
Apologies I thought I had. It's part C that I'm struggling with.
One of a few ways that I have got to 4.4 is by using s=.5*a*t^2 (as u = 0, or that's the way I understood the question) a is given as 6.9 and t can be calculated from a bit of Pythagoras and suvat to be around 1.1322 (depending on the accuracy which may be a source of error for me) putting it in the equation got me 4.4 (2 s.f) which is wrong and gets the message mentioned above.
I'm struggling to get the correct answer on the attached problem, the answer I keep getting is 4.4 (2s.f) for which it tells me the sign at some point during my calculation is incorrect even if I try to reverse engineer the problem (use different values of s till I get the correct value for t) I still get 4.4. I'm not sure if my understanding of the question is wrong or my calculations are wrong. If it would help I can post my answers to the previous parts.
Apologies I thought I had. It's part C that I'm struggling with.
One of a few ways that I have got to 4.4 is by using s=.5*a*t^2 (as u = 0, or that's the way I understood the question) a is given as 6.9 and t can be calculated from a bit of Pythagoras and suvat to be around 1.1322 (depending on the accuracy which may be a source of error for me) putting it in the equation got me 4.4 (2 s.f) which is wrong and gets the message mentioned above.
It seems that you have interpreted the part C of the question wrongly.
Let the time taken for the player to move from B to C be Δt.
The player speeds up uniformly (constant acceleration with magnitude a) for a duration of 0.5Δt and then slows down uniformly (constant acceleration with magnitude a) for the next 0.5Δt.
The Δt is NOT 1.1322 s NOT because of the precision
It seems that you have interpreted the part C of the question wrongly.
Let the time taken for the player to move from B to C be Δt.
The player speeds up uniformly (constant acceleration with magnitude a) for a duration of 0.5Δt and then slows down uniformly (constant acceleration with magnitude a) for the next 0.5Δt.
The Δt is NOT 1.1322 s NOT because of the precision
I said the wrong question sorry. I meant to say part D.
Apologies I thought I had. It's part C that I'm struggling with.
One of a few ways that I have got to 4.4 is by using s=.5*a*t^2 (as u = 0, or that's the way I understood the question) a is given as 6.9 and t can be calculated from a bit of Pythagoras and suvat to be around 1.1322 (depending on the accuracy which may be a source of error for me) putting it in the equation got me 4.4 (2 s.f) which is wrong and gets the message mentioned above.
If it is part D, this description makes senses. Actually, your working makes no sense because the player needs to reach zero velocity before moving in the opposite direction.
The above graph (velocity versus time) describes the problem and what you need to solve for the problem. At time t, the player changes the direction of acceleration. For the next Δt (which was what you calculated, Δt = 1.132 s) duration, the player is trying to move back to B.
Ah so that Δt is the time the player has to deaccelerate to zero and accelerate to B. I think I got confused with the instantaneous part. Thanks
You can say so. I would not suggest using words like decelerate or deceleration but as long as you know what you are describing, I think it is good.
I find part D too and need to read the question a few times before knowing what the question is asking. IMO the confusing phrase is the “maximum distance”…
You can say so. I would not suggest using words like decelerate or deceleration but as long as you know what you are describing, I think it is good.
I find part D too and need to read the question a few times before knowing what the question is asking. IMO the confusing phrase is the “maximum distance”…
Ok, thank you. Would you be able to give any more pointers on how to get to the right answer as I still seem to be making mistakes?
And the value/s of t that I get can be used in s= ut + .5at^2, where u = 0 so s = .5*at^2 ?
Yes and no. You have to think what is the meaning of the displacement that you obtain from s= 0.5*a*t^2. Physics is NOT plug in the value and calculate. You need to think about what the meaning of the answer.