Question

You’re driving at 70 km/h when you apply constant acceleration to pass another car. six seconds later, you’re doing 80 km/h. how far did you go in this time?

Answer 1

To solve this problem, we must use the equations of motion. We are given the following values:

vi = initial velocity = 70 km / h

vf = final velocity = 80 km / h

t = time taken = 6 s  = (6 / 3600) h

d = distance travelled = ?

a = acceleration = ?

Specifically, the formulas we have to use are:

a = (vf – vi) / t

d = vi * t + 0.5 a t^2

So first, solving for the acceleration a:

a = (80 – 70) / (6 / 3600)

a = 6,000 km / h^2 = 0.46 m/s^2

 

Now solving for d:

d = 70 (6 / 3600) + 0.5 (6000) (6 / 3600)^2

d = 0.125 km

or

d = 125 m