Momentum is a measure of an object's mass and velocity. The forces that influence momentum are the same forces that influence velocity, as momentum is directly related to velocity. Here's a breakdown:

Forces that directly influence momentum:

* Net Force: This is the most fundamental force. Newton's Second Law of Motion states that the net force acting on an object is equal to the rate of change of its momentum.

* Example: If you push a box, you apply a force that changes its momentum. The harder you push (greater force), the faster the momentum changes.

Forces that indirectly influence momentum:

* Gravity: A constant force pulling objects towards the center of the Earth (or any other celestial body). It can affect the velocity of an object, thus changing its momentum.

* Example: A ball thrown upwards will slow down due to gravity, decreasing its momentum.

* Friction: A force that opposes motion between two surfaces in contact. Friction can slow an object down, reducing its momentum.

* Example: A car rolling to a stop due to friction between the tires and the road.

* Air Resistance: A force that opposes the motion of objects through the air. Similar to friction, it can slow objects down, decreasing their momentum.

* Example: A parachute increases air resistance, slowing down a skydiver's momentum.

Important points to remember:

* Momentum is a vector quantity: It has both magnitude (amount) and direction.

* Conservation of Momentum: In a closed system (where no external forces act), the total momentum remains constant. This means that momentum can be transferred between objects, but it is not lost or gained.

Let me know if you'd like a more detailed explanation of any of these forces!