In: Physics
In outer space rock 1, with mass 3 kg and velocity < 3500,
-2500, 3200 > m/s, struck rock 2, which was at rest. After the
collision, rock 1's velocity is < 3000, -1800, 3500 > m/s.
What is the final momentum of rock 2?
2f =
kg · m/s
Before the collision, what was the kinetic energy of rock 1?
K1i = J
Before the collision, what was the kinetic energy of rock 2?
K2i = J
After the collision, what is the kinetic energy of rock 1?
K1f = J
Suppose the collision was elastic (that is, no change in kinetic
energy and therefore no change in thermal or other internal energy
of the rocks). In that case, after the collision, what is the
kinetic energy of rock 2?
K2f = J
On the other hand, suppose that in the collision some of the
kinetic energy is converted into thermal energy of the two rocks,
where Ethermal,1 +
Ethermal,2 = 4.46 ⨯ 106 J. What is
the final kinetic energy of rock 2?
K2f = J
In this case (some of the kinetic energy being converted to thermal
energy), what was the transfer of energy Q (microscopic
work) from the surroundings into the two-rock system during the
collision? (Remember that Q represents energy transfer due
to a temperature difference between a system and its
surroundings.)
Q = J
What is the final momentum of rock 2 ?
use conservation of momentum
m1v1i + m2v2i = m1v1f + m2v2f
3 < 3500, -2500, 3200 > + 0 = 3 < 3000, -1800, 3500 > + p2f
so,
p2f = <1500, -2100, -900> Kg.m/s
____________________
Before the collision, what was the kinetic energy of rock 1
K1i = 1/2 * 3 * (35002 + 25002 + 32002)
K1i = 4.311e7 J
_________________
Before the collision, what was the kinetic energy of rock
2?
K2i = 0 J
____________
After the collision, what is the kinetic energy of rock 1?
K1f = 1/2 * 3 * (30002
+ 18002 + 35002 )
K1f = 3.673e7 J
___________
K2f = 4.311e7 - 3.673e7
K2f = 6.375e6 J
____________
On the other hand, suppose that in the collision some of the
kinetic energy is converted into thermal energy of the two rocks,
where Ethermal,1 +
Ethermal,2 = 4.46 ⨯ 106 J. What is
the final kinetic energy of rock 2?
K2f = 6.375e6 -
4.46e6
K2f = 1.92e6 J
___________