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.