Acceleration/Velocity/Speed Physics Problem?

Question

A car moves at 12 m/s and coasts up a hill with uniform acceleration of -1.6 m/s^2. How far has the car traveled after 6.0 s?

Soo I'm trying to decide what equation to use... D=VT?
I'm not sure if the 12 m/s if velocity or speed.
Could someone show me how to do this please?

Answer 1

In this case we should not use D=VT, as this should be used when the speed is constant.

In our case the speed is decreasing at each moment.

Hence use the following formula

d = u*t + 0.5*a*(t^2)

d = unknown (distance travelled)
u = 12m/s (initial speed)
t = 6s (time taken to travel)
a = -1.6 m/s^2 (acceleration or deceleration in our case)

d = 12*6 - 0.5*1.6*6*6
= 43.2m

Answer 2

Sadly, this problem is not as simple as distance, time and velocity.

the note about the car's acceleration from going up hill complicates things.

for that type of problem, you need the equation:

d = V(initial) * t + 1/2 a * t^2

Fortunately, you have V, a and t, so this is just a matter of plugging in and chugging out the number.

V(initial) = 12 m/s
a = -1.6m/s^2
t = 6.0 s

d = 12 * 6 - 0.8 * 36 = 43.2 m

Answer 3

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