Question

For the system form of the basic laws, the momentum of a system can change as a result of: a. pressure acting on the system. b. friction acting on the system. c. gravity acting on the system. d. body forces acting on the system. e. surface forces acting on the system. f. all of the above.

Answer 1

Answer: F. All the above.

Explanation:

Basically, if an object is moving, it moves with a certain velocity and mass. Momentum of a body is a product of mass and velocity. The sum of momentum of individual bodies is equal to the entire system momentum. For instance, a block v is moving due to an applied force F, with a velocity V and the gravity g. Due to gravity, the weight is mg. Due to gravity, the weight is acting downward. Applied force is acting on the block surface area A.

Pressure = Surface force/Surface area.

Surface force is acting on the surface applied. So, acting pressure = Force applied/area.

Pressure and surface force is acting on the body. Body forces also act on the system. Forces due to gravity is also referred to as body force. As a result of weight of the box, Normal force produced by the rough surface is equal to the Weight. As a result of rough surface, frictional forces are produced which opposes the block to move forward. All the external forces create a net total force due to which the block move with a velocity and acceleration.

In Newton's second law, Ftotal is equal to mass × acceleration.

Therefore, we can conclude that momentum can change as a result of all these forces because mass × acceleration is related to total force and momentum is equal to mass × velocity.

Answer 2

Answer:

Option f

All of the above

Explanation:

Considering a control volume, the system form shows that the change in momentum is affected by any force at all on the system, this includes, pressure force, frictional force, gravity force, or any other body or surface forces on the system.

For steady flow with a fixed control volume, the most useful form of the momentum equation is given as:

$\Sigma F_{gravity}+\Sigma F_{pressure}+\Sigma F_{viscosity}+\Sigma F_{other}=\Sigma mV_{av}$

This shows that all forces, whether body forces or contact forces present in the system can affect the momentum of the system.