. An object has a position given by ~r(t) = [3.0 m − (4.00 m/s)t]ˆı + [6.0 m − (8.00 m/s2 )t 2 ]ˆ , where all quantities are in SI units. What is the magnitude of the acceleration of the object at time t = 5.00 s? (a) 8.94 m/s 2 (b) 0.00 m/s 2 (c) 16.0 m/s 2 (d) 8.00 m/s 2 (e) 4.00 m/s 2

(c) 16 m/s²

Explanation:

The position is .

The velocity is the first time-derivative of r(t).

The acceleration is the first time-derivative of the velocity.

Since a(t) does not have the variable t, it is constant. Hence, at any time,

Its magnitude is 16 m/s².

the independent variable, the one that is intentionally manipulated, is whether or not the car hits the barrier.

the dependent variable, the one that you measure the response in, is the distance that the washers travel.