Calcular desde qué altura debe caer en punto muerto un automóvil de 7.000 n de peso para que adquiera la misma energía cinética que si marchase a 90 km/h

31.9 m

Explanation:

First of all, let's start by calculating the mass of the object, which is given by

where

W = 7000 N is the weight

g = 9.8 m/s^2 is the acceleration of gravity

Substituting,

Now, we want this object to have the same energy as its kinetic energy when it travels at

So when its kinetic energy is

The gravitational potential energy is given by

where h is the heigth of the object. We want the object to have the same energy as calculated for K, so we write

U = K

and solving for h, we find

d. platinum would have the greatest temperature increase because it has the lowest specific heat.