Understanding the Relationship Between Force, Momentum, and Impulse

  • Context: High School 
  • Thread starter Thread starter zeshkani
  • Start date Start date
  • Tags Tags
    Force Momentum
Join the discussion
Ask a follow-up here, or get your own question answered by working scientists, mathematicians and engineers — people, not an autocomplete.
Real named experts · corrections over time · the nuance an AI answer skips
4 replies · 7K views
zeshkani
Messages
28
Reaction score
0
Is force related to Momentum or momentum to force in anyway
F=ma and P=mv
 
Physics news on Phys.org
Yes, the link between the two is time. Essentially, force is applied over time to change an objects momentum.

Because F = m a, and a =[tex]\Delta[/tex]v / t
then F = m v/t
As you said P = mv so we get
F = P/t or P = Ft
 
With calculus, the equations become more instantaneous and exact:

F=ma=m(dv/dt)=dp/dt-v(dm/dt).

If dm=0 (for instance, not a rocket) then:

F=dp/dt
 
Also, do you know the concept of Impulse? It has the same dimensions of momentum, but is more precisely defined as a Force acting over a certain amount of time. That's why when you drop an egg on a pillow, it will not break, but when you drop an egg on concrete, it will. Because the egg has some mass m and velocity v, and therefore some momentum p = mv, this momentum is numerically equal to the reactive force of the ground(or pillow) multiplied by the time interval it spends on that respective surface.

The pillow cushions the fall and therefore increases the time interval, in effect decreasing the force and keeping the egg from breaking. When you drop it on the concrete, the time interval is very short, and so the force on the egg is large (which is why it breaks).