Choose the correct alternative: The rate of change of total momentum of a many particle system is proportional to the external force/sum of the internal forces on the system.

The rate of change of total momentum of a system of many particle system is proportional to the cdots on the system

The rate of change of linear momentum of a body is directly proportional to the external force applied on it,and takes place always in the direction of force applied. Name this law.

The rate of change of linear momentum of a body is directly proportional to the external force applied on it,and takes place always in the direction of force applied. Using the law obtain the expression for force.

The rate of change of linear momentum of a body is directly proportional to the external force applied on it,and takes place always in the direction of force applied. The motion of a particle of mass m is described by y = ut+1/2gt^2. Find the force acting on it.