# The car starts to move in the direction of the north and picks up speed 72 km / h in 40 seconds.

**The car starts to move in the direction of the north and picks up speed 72 km / h in 40 seconds. Consider the movement of the car as straight-line uniformly accelerated. a) How is the acceleration of the car directed? b) What is the modulus of the vehicle’s acceleration? c) Draw a graph of the projection of vehicle speed versus time. d) What was the speed of the car 10 seconds after the start of the movement?**

Vo = 0 m / s.

V = 72 km / h = 20 m / s.

t = 40 s.

t1 = 10 s.

a -?

V1 -?

Let us write down the formula for determining the acceleration a: a = (V – Vо) / t.

a = (20 m / s – 0 m / s) / 40 s = 0.5 m / s ^ 2.

From the acceleration formula, we express the speed: V = Vo + a * t.

V = 0.5 m / s ^ 2 * t.

As the car starts to move, its speed increases, which means that the acceleration is directed in the direction of movement. Acceleration is directed to the north.

V1 = Vo + a * t1.

V1 = 0 m / s + + 0.5 m / s ^ 2 * 10 s = 5 m / s.

Answer: the acceleration is directed to the north, the acceleration of movement is a = 0.5 m / s ^ 2, the speed in 10 s V1 = 5 m / s.