8-82 A
football of mass 0.41 kg is kicked from
rest and given a velocity of 24 m/s at 29° above the horizontal.
The ball is in
contact with the kicker's foot for 8.2 ms. Determine:
(a) the
horizontal and vertical components of
the ball's momentum
(b) the
horizontal and vertical components of
the average force exerted by the foot on the ball (using momentum
methods)
(c) the
magnitude and direction of the force in
(b).
[Ans. (a) 8.6
kg m/s; 4.8 kg m/s (b) 1.0X103
N; 5.8X102 N (c) 1.2X103 N at 29°above
horizontal]
ACCUMULATED
SOLUTION
Correct!
Any of the
four coordinate systems could be
used but this is the best.
The initial
(i) and final (f) components of momentum
are:
|
- |
px,i |
px,f |
py,i |
py,f |
|
0 |
mv sin 29 |
0 |
mv cos 29 |
|
|
mv cos 29 |
0 |
mv sin 29 |
0 |
|
|
0 |
mv cos 29 |
0 |
mv sin 29 |
|
|
mv sin 29 |
0 |
mv cos 29 |
0 |