Question

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Answer 1

the car is at rest when the velocity is zero

Answer 2

I got 12.5

Answer 3

It looks like you need to first find the formula for the velocity
by taking the derivative of distance with respect to time.

Answer 4

start with
s(t) = 50t - 2t^2,
and
ds/dt = 50 - 4t
and you want the value of t when ds/dt (i.e. the velocity) is 0

Answer 5

12.5

Answer 6

so I solve for t?? I still get 12.5?

Answer 7

yes, you set velocity to 0:
0 = 50 - 4t
add +4t to both sides
4t= 50
divide both sides by 4

Answer 8

ok thanks so much!!