Newton's second law states that the force applied to an object is equal to the product between the mass m of the object and its acceleration a: [tex]F=ma[/tex] Using [tex]m=65 kg[/tex] and [tex]a=5 m/s^2[/tex], we can find the value of the force applied to the roller-blade to obtain this acceleration: [tex]F=(65 kg)(5 m/s^2)=325 N[/tex]