alexander (jra2623) – oldhomework 18 – Turner – (92510)
1
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001
10.0 points
A 0.499 kg bead slides on a straight friction
less wire with a velocity of 4.68 cm/s to the
right, as shown. The bead collides elastically
with a larger 0.600 kg bead initially at rest.
After the collision, the smaller bead moves to
the left with a velocity of 0.68 cm/s.
0
.
499 kg
4
.
68 cm
/
s
0
.
6 kg
Find the distance the larger bead moves
along the wire in the first 4.3 s following the
collision.
Correct answer: 19
.
1683 cm.
Explanation:
Basic Concepts:
m
1
vectorv
1
,i
=
m
1
vectorv
1
,f
+
m
2
vectorv
2
,f
since
v
2
,i
= 0 m/s.
Δ
x
=
v
Δ
t
Given:
Let to the right be positive:
m
1
= 0
.
499 kg
v
1
,i
= +4
.
68 cm
/
s
m
2
= 0
.
600 kg
v
1
,f
=
−
0
.
68 cm
/
s
t
= 4
.
3 s
Solution:
v
2
,f
=
m
1
v
1
,i
−
m
1
v
1
,f
m
2
=
(0
.
499 kg)(4
.
68 cm
/
s)
0
.
6 kg
−
(0
.
499 kg)(
−
0
.
68 cm
/
s)
0
.
6 kg
= 4
.
45773 cm
/
s
to the right.
Thus
Δ
x
= (4
.
45773 cm
/
s)(4
.
3 s)
= 19
.
1683 cm
002
(part 1 of 2) 10.0 points
Consider the collision of two identical parti
cles, with
m
1
=
m
2
= 10 g.
The initial velocity of particle 1 is
v
1
and
particle 2 is initially at rest,
v
2
= 0 m/s..
1
2
v
1
After an elastic headon collision, the final
velocity of particle 2 is
v
′
2
and given by
1.
v
′
2
= 2
v
1
2.
v
′
2
=
v
1
correct
3.
v
′
2
=
v
1
4
4.
v
′
2
=
2
v
1
3
5.
v
′
2
= 0
6.
v
′
2
=
4
v
1
3
7.
v
′
2
=
5
v
1
3
8.
v
′
2
=
v
1
2
9.
v
′
2
=
3
v
1
4
10.
v
′
2
=
v
1
3
Explanation:
For the final velocity of particle 2 after an
elastic collision, we have
v
′
2
= 2
v
cm
−
v
2
.
For the present case,
v
cm
=
m
1
v
1
+
m
2
v
2
m
1
+
m
2
=
v
1
2
.
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alexander (jra2623) – oldhomework 18 – Turner – (92510)
2
So
v
′
2
= 2
parenleftBig
v
1
2
parenrightBig
−
0 =
v
1
.
003
(part 2 of 2) 10.0 points
Next replace particle 1 by a sledge hammer
with mass
m
1
= 10 kg, particle 2 by a golf
ball with a mass
m
2
= 10 g.
Consider the
elastic headon collision between the hammer
and the ball.
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 Summer '08
 Kaplunovsky
 Friction, Kinetic Energy, Mass, Momentum, Work, kg, Alexander

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