Momentum Quiz 1

Center of Mass

The average position of the particles of matter in an object or a system

The place of a Center of mass can be

Empty space

Why is the center of mass important

Gives a point of application for weight, objects rotatet around the center of mass when left to themselves,

When an object moves, the center of mass moves …

as a single particule would, with the same mass as the system and subject to the same external forces

The (velocity) of the center of mass …. (also applied to acceleration/displacement)

Equals the weighted average of velocity in the system of particles

What would be Newtons Second law applied to a system of particles ?

Mass of the system times the acceleration of the center of mass of the system is equal to the Net external force

why do only external forces change the systems motion ?

Because Inside a system particles follow newtons third law

Momentum

Inertia in motion

If an object has inertia and its moving …

it will want to continue moving

Equation of momentum

m ⋅ v —> kgm/s

How did Newton originally right the second law

Fn= p/t

What does the t in P/t demonstrate ?

That the quicker the time, the bigger the force

What determines if the magnitude of momentum

Mass (resistance an object offers), Velocity (size of change in motion)

The total momentum of a system of particles …

Equals the mass od that system of particles times the velocity of the center of mass

Law of conservation of momentum not apply to ….

Individual objects

Law of conservation of momentum

If the net force acting on a system of ojects is zero, the total momentum of that system remains unchanged

In the law of conservation of Momentum the observer …

Decides the system, so according to that reference frame some external forces could also be conserved

Explain the law of conservation of momentum with properties (math)

if no external forces are acting, the acceleration is 0, hence the velocity is constant so the total momentum of the system stays the same.

If a force only acts on the y-axis how is the momentum on the x-axis affected……..

It conserves momentum

Why is momentum efficient ? (point of reference between two observers)

If there are two observers at different points of reference, they may disagree on the velocity of the object, but they will agree on the conservation of momentum

two objects of different masses that have the same momenta, dont have the same KE , why ?

Although mass is smaller, KE depends on the square of the speed hence the speed would quadrupel regardless of the small mass