Unos rieles de acero de 15 m de longitud son colocados en un día en que la temperatura es de 3 grados celcius ¿cual será el espacio mínimo que habrá de dejar entre ellos para que lleguen justo a Ricarda un día en que la temperatura sea de 48 grados celcius

because growing process had stoped after 4-5 year

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

                                              ⇒      

here   k is the proportionality constant whose value is 1.

                                                            [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.