Ch9 HW2 (Homework)
Arthur Barfield
PHYS 2211, section M, Fall 2008
Instructor: Jennifer Curtis
Web
Assign
Current Score:
58 out of 59
Due:
Friday, October 31, 2008 09:00 AM EDT
Description
Momentum and energy in collisions: Unequal masses; 2D collisions
Instructions
Reading: CH9
The due date for this assignment is past.
Your work can be viewed below, but no changes
can be made.
1.
9/9 points
In outer space rock 1, with mass
6
kg and velocity <
3700
,
-3200
,
1800
> m/s, struck rock 2,
which was at rest. After the collision, rock 1's velocity is <
3200
,
-2700
,
2100
> m/s. What is the
final momentum of rock 2?
2
f
= <
3000
3000
,
-3000
-3000
,
-1800
-1800
> kg
·
m/s
Before the collision, what was the kinetic energy of rock 1?
K
1
i
=
8.151e7
8.15e+07
J
Before the collision, what was the kinetic energy of rock 2?
K
2
i
=
0
0
J
After the collision, what is the kinetic energy of rock 1?
K
1
f
=
6.582e7
6.58e+07
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?
K
2
f
=
1.569e7
1.57e+07
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
E
thermal,1
+
E
thermal,2
=
1.10
10
7
J. What is the final
kinetic energy of rock 2?
K
2
f
=
4.69e6
4.69e+06
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