This preview shows page 1. Sign up to view the full content.
8.3.
IDENTIFY
and
SET UP:
p
mv
.
2
1
2
K
mv
.
EXECUTE:
(a)
p
v
m
and
2
2
1
2
2
pp
Km
mm
.
(b)
cb
KK
and the result from part (a) gives
22
.
b
b
c
c
c
c
0.145 kg
1.90
0.040 kg
m
p
p
p
p
m
. The baseball
has the greater magnitude of momentum.
/
0.526
.
(c)
2
2
p
mK
so
mw
gives
m
m
w
w
m K
m K
.
w mg
, so
m
m
w
w
w K
w K
.
m
w
m
m
m
w
700 N
1.56
450 N
w
K
K
K
K
w
.
The woman has greater kinetic energy.
/
0.641
.
8.12.
IDENTIFY:
Apply Eq. 8.9 to relate the change in momentum of the momentum to the components of the
average force on it.
SET UP:
Let +
x
be to the right and +
y
be upward.
EXECUTE:
(a)
21
(0.145 kg)( [65.0 m/s]cos30
50.0 m/s)
15.4 kg m/s
x
x
x
x
J
p
mv
.
(0.145 kg)([65.0 m/s]sin30
0)
4.71 kg m/s
y
y
y
y
J
p
mv
mv
The horizontal component is 15.4 kg m/s
, to the left and the vertical component is 4.71 kg m/s
, upward.
(b)
av
3
15.4 kg m/s
8800 N
1.75 10 s
x
x
J
F
t
.
av
3
4.71 kg m/s
2690 N
y
y
J
F
t
.
The horizontal component is 8800 N, to the left, and the vertical component is 2690 N, upward.
EVALUATE:
The ball gains momentum to the left and upward and the force components are in these directions.
8.16.
IDENTIFY:
Apply conservation of momentum to the system of you and the ball. In part (a) both objects have
This is the end of the preview. Sign up
to
access the rest of the document.
 Fall '07
 Evrard

Click to edit the document details