A force F is applied on a block of mass M. the block is displaced through a distance d in the direction of the force. What is the work done by the force on the block? Does the internal energy change because of this work?

1. Work done by the force on the block is Fd.


Explanation


Given


Force =F


Displacement due to force = d


We know that


Work done= force × displacement × cos θ


θ in our case is zero as displacement is in the direction of the force.


Work done by the force = F ×d ×cos 0


=F ×d ( cos0=1)


Work done by the force on the block is F ×d.


2. Internal energy will not change because of work done by the force on the block.


Explanation


Internal energy is defined as the sum of the kinetic energy and potential energy of molecules of the system. It includes only the energy associated with the random motion of molecules of the system.


If the block moves as a whole system with some velocity, the kinetic energy of the box is not to be included in internal energy.


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