# Homework Help: Need a little push. [Simple Physics Problems]

1. Sep 13, 2016

### Emilyneedshelp

1. The problem statement, all variables and given/known data
Question
A car starts from rest and uniformly increases its speed at a rate of 0.7 m/s2 on a circular track of radius R = 253 m. What is the magnitude of the car’s net acceleration after 50 s?

acen=.7m/s^2
t=50s
R=253m

2. Relevant equations
Equations
acen=(v^2)/r
Maybe?
ω=Δθ/Δt
a=r(Δω/Δt)

3. The attempt at a solution
√[aT^2 + aC^2]

aC=.7m/s^2
aT= r(dω/dt)

√[.7(253)]=v
v=13.308m/s

v(50s)=S
S=665.4

S/r=θ

ω/50=α

α(253)=aT

aT=.26616
a=√[aT^2 + aC^2]
a=.74489m/s^2

Answer is not correct, is there something wrong with my logic?

2. Sep 13, 2016

### billy_joule

The given acceleration is how fast the cars speedometer is changing. (I.e.the change in the magnitude of the tangential velocity with time).
Not acen as you've used it.

3. Sep 13, 2016

### Emilyneedshelp

Thank you, I solved it. How silly of me not to realize that.