A horse pulling a cart has to apply a greater force to start the cart than to keep the cart in motion Why ?

"A horse has to apply more force to start a cart than to keep it moving ". Why?

A horse pulls a cart with constant force so that the cart moves with a constant speed. Will the speed of the cart increase,decrease or remain the same if the horse applied more force?

A horse pulls a cart with constant force so that the cart moves with a constant speed. Does it violate Newtons second law of motion?

A horse pulls a cart with constant force so that the cart moves with a constant speed. How will you account for the non-acceleration of the cart?

When a horse pulls a cart, which force helps the horse to move forward ?

A horse continues to apply a force in order to move a cart with a constant speed. Explain why?