II. LAW OF __________________________________
In a closed
system:
Collision
Problems
Example 1)
A 3 kg object traveling 6 m/s east
has a perfectly elastic collision with a 4 kg object traveling 8 m/s west. After
the collision, the 3 kg object will travel 10 m/s west.
1)
Find the
total momentum BEFORE the collision.
Total momentum before =
2)
What is the
total momentum after the collision?
3)
What is the
velocity of the 4 kg object after the collision?
Example 2)
A 10 kg Block A moves with a
velocity of 2 m/s to the right and collides with a 10 kg Block B which
is at rest. After the collision Block A stops moving and Block B moves
to the right.
a) Find the total momentum
after the collision
b) Find the velocity of
Block B after the collision.
Example 3)
A 10 kg cart moving with a velocity of 10
m/s East collides and attaches itself to a 10 kg cart moving at a velocity of
50 m/s west.
Draw a quick picture
1) Find the total momentum
before the collision
2) Find the total momentum
after the collision
3) What is the velocity of
the attached carts after the collision?
B) Recoil Problem - When
interacting objects start from rest
Example
1) A 4 kg rifle fires a 5 x 10-3 kg bullet at a velocity of
500 m/s. What is the velocity acquired by the rifle?
Total
Momentum Before Interaction =
Total Momentum After Interaction
_____________________________
Why is the total momentum before Zero???
Subtract m2v2 from both sides
_____________________
In problem Solving, remove negative sign
and use
__________________
(Not in Reference Table) *********
Important:
Regents almost always has an question that
asks you to use this equation
Example 2) 2
magnets of 1 kg and .5 kg are arranged at
rest on a horizontal frictionless surface. When the strings holding them
together is cut they move apart under the magnetic force of repulsion.
a) What is the total momentum of the
magnets before the string is cut?
b) What is the total momentum of the
magnets after the string is cut?
c) What is the velocity of the .5 kg mass
when the velocity of the 1 kg magnet is 30 m/s?