A car initially traveling eastward turns north by traveling in a circular path a

Physics
Tutor: None Selected Time limit: 1 Day

A car initially traveling eastward turns north by traveling in a circular path at uniform speed as in the figure. The length of the arc ABC is 270 m, and the car completes the turn in 31.0 s.

(a) Determine the car's speed.
 m/s

(b) What is the magnitude and direction of the acceleration when the car is at point B?
magnitude      m/s2
direction  ° counterclockwise from the +x-axis 

Jun 8th, 2015

Thank you for the opportunity to help you with your question!

The length of the arc is for a 90 degree or (π/2) radians is 
l = rθ 
l = 270*(π/2) 
l = 424.1 m 

so the constant speed is 
v = l/t 
v = 424.1 / 31 
v = 13.68 m/s 

acceleration at a uniform speed on a circular curve is 
a = v²/r 
a = 13.68² / 270 
a = 0.693 m/s² 

and the direction will be towards the center of the curve which will be perpendicular to the instantaneous velocity. 
35° + 90° = 125°

Please let me know if you need any clarification. I'm always happy to answer your questions.
Jun 8th, 2015


Jun 8th, 2015

ok so this is the graph 

Jun 8th, 2015

yes because the answer is not correct 

Jun 8th, 2015

all of them?

Jun 8th, 2015

yes all 

Jun 8th, 2015

ok hold up I'll get back to you ASAP

Jun 8th, 2015

ok


Jun 8th, 2015

(a) tangential speed is v = s / t = 270m / 31s = 8.71 m/s 

(b) radius is r = s / θ = 270m / pi/2 = 172m 

a = v^/r = 8.71^2 / 172 = 0.441 m/s^2 at angle 180-35 deg = 145deg CCW from x-axis 
(towards the origin)

let me know if this is right

Jun 8th, 2015

b is not but a is correct and where is c

Jun 8th, 2015

b) 0.441 m/s^2, 45

is this what you wrote? 

Jun 8th, 2015

yes and it is correct but where the direction c


Jun 8th, 2015

45

Jun 8th, 2015

no is not the correct answer

Jun 8th, 2015

is that +, - direction for you to choose or?

Jun 8th, 2015

yes there is 

Jun 8th, 2015

which one i should choose - or +

Jun 8th, 2015

?

Jun 8th, 2015

try 145 degree - direction

Jun 8th, 2015

no

Jun 8th, 2015

last try so please try to be correct 

Jun 8th, 2015

both the degree and the direction are incorrect?

Jun 8th, 2015

yes

Jun 8th, 2015

in same box so if any one is not correct the other will be the some 

Jun 8th, 2015

try 55 + direction

Jun 8th, 2015



Jun 8th, 2015
screen_shot_2015_04_28_at_5.53.17_pm.png
screen_shot_2015_06_07_at_10.24.16_pm.png
screen_shot_2015_06_07_at_10.51.31_pm.png

Your response differs significantly from the correct answer. Rework your solution from the beginning and check each step carefully.° counterclockwise from the +x-axis  that what i get when i put the answer 

Jun 8th, 2015

you are not supposed to put +/- in front of the number, just put 55

Jun 8th, 2015

ok


Jun 8th, 2015

if it's still not right let me know

Jun 8th, 2015

not correct

Jun 8th, 2015

did you try to put 145 before? just 145

Jun 8th, 2015

ok the web is not open any more time over thanks a lot for trying to help me I appreciate that

Jun 8th, 2015

ok the web is not open any more time over thanks a lot for trying to help me I appreciate that

Jun 8th, 2015

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