A woman drives 10 miles, accelerating uniformly from rest to 70 mph. How long does it take for her to reach 70 mph?

Question

anonymous · Answer

v = u + at

v = her final velocity
u = her initial velocity
a = acceleration
t = time take (which you are finding)

anonymous · Answer

what's acceleration in this case?

anonymous · Answer

oh sorry.
u need a different equation

anonymous · Answer

hold on

anonymous · Answer

first find her acceration
$$v ^{2} = u ^{2} + 2as$$
then use v = u + at

anonymous · Answer

for kinematics, you need 3 equations and u  can solve everything

anonymous · Answer

ill post them for you. copy them somewhere

anonymous · Answer

$$v = u + at$$
$$v ^{2} = u ^{2} + 2as$$
$$s = ut + \frac{ 1 }{ 2 }at ^{2}$$

anonymous · Answer

ok what's s?

anonymous · Answer

s = displacement
remember these are vectors so direction matters as that decides whether the value is positive or negative