A car with two driving axles, under the action of a traction force of 800 N, increased its speed from

A car with two driving axles, under the action of a traction force of 800 N, increased its speed from 36 km / h to 72 km / h on a certain segment of the horizontal path. Determine the time during which the speed change occurred, and the distance traveled during this time. Vehicle weight 1200 kg.

Since, according to the conditions of the problem, the friction force is not indicated, the solution will be carried out without taking it into account.

So, the acceleration that is imparted to the car by the traction force is found by the formula:

a = F / m, where – F – traction force, N, m – vehicle mass, kg.

Also, the acceleration can be found from another formula:

a = (V2 – V1) / t, where V1, V2 are the initial and final speeds (we convert km / h into m / s), t is the time

combining both of these formulas, we get:

(V2 – V1) / t = F / m, hence t = m * (V2 – V1) / F = 1200 * (20 – 10) / 800 = 15 s.

Answer: 15 seconds