Answer:

Explanation:
According to the law of conservation of linear momentum, the total momentum of both pucks won't be changed regardless of their interaction if no external forces are acting on the system.
Being
and
the masses of pucks a and b respectively, the initial momentum of the system is

Since b is initially at rest

After the collision and being
and
the respective velocities, the total momentum is

Both momentums are equal, thus
Solving for 


The initial kinetic energy can be found as (provided puck b is at rest)


The final kinetic energy is


The change of kinetic energy is

Answer:
The input force (effort) is the amount of effort used to push down on a rod, or pull on a rope in order to move the weight. In this example, the force the little guy is using to pull the elephant is the input force.
Explanation:
Answer:
a)
, b) 
Explanation:
a) The magnetic force experimented by a particle has the following vectorial form:

The charge of the electron is equal to
. Then, cross product can be solved by using determinants:

The magnetic force is:

b) The charge of the proton is equal to
. Then, cross product has the following determinant:

The magnetic force is:
