4. Un móvil lleva una velocidad de 75 m/s, en dicho momento aplica los frenos durante tiempo de 15 segundos hasta detenerse. ¿cuál será la aceleración del frenado? ¿cuál es la distancia que recorre hasta detenerse?

a = 5 m / s²   and    x = 562.5 m

Explanation:

Let's apply the kinematics relations

          v = v₀ + at

          v² = v₀² + 2a x

In this case, as the car stops, its final speed is zero (v = 0) and the acceleration must be opposite to the speed, that is, negative

           0 = v₀ - a t

           a = v₀ / t

let's calculate

           a = 75/15

           a = 5 m / s²

let's look for the distance

           0 = v₀² - 2a x

           x = v₀² / 2a

let's calculate

           x =

           x = 562.5 m

a.metals can become magnetic if they have many spinning electrons that create magnetic fields.d.only some metals are attracted by magnets; these metals are called ferromagnetic.

d.wrapping an insulated wire around a metal with ferromagnetic properties and applying an electric current.