Q8:

You are participating in the Iditarod, and
your sled dogs are pulling you across a frozen lake with a force of
1
2
0
0
N
while a 300 N wind is blowing at you at 135 degrees from your direction of
travel.

What is the total forward force?

Does the wind increase or decrease your
kinetic energy?

Q13:

A couch is repositioned on a horizontally aligned living room floor. The first
repositioning of the couch involves pushing the couch a distance of
3.0 m parallel to one wall
of the room, and then a distance of
1.0 m perpendicular to the
3.0 m distance. The second
repositioning of the couch returns the couch to its initial position, but this time
without any change of direction. The normal reaction force on the couch from the floor
is 1.0 kN and the coefficient of
kinetic friction between the couch and the floor is 0.60.

How much work is done by friction on the couch during its first repositioning?

How much total work is done against friction by the couch during both of its repositionings?

Q14:

An object moves along a parabolic path
𝑃
1
, corresponding to the equation
𝑦
=
(
0
.
5
0
0
)
𝑥
m
−
1
2
from the origin
𝐴
=
(
0
.
0
,
0
.
0
)
m to the point
𝐵
=
(
2
.
0
,
2
.
0
)
m
under the action of a force
⃑
𝐹
=
(
5
.
0
/
)
𝑦
⃑
𝑖
+
(
1
0
/
)
𝑥
⃑
𝑗
N
m
N
m
The same object moves along the path
𝑃
2
, corresponding to the
equation
𝑦
=
(
0
.
2
5
0
0
)
𝑥
m
−
2
3
,
also from the origin
𝐴
=
(
0
.
0
,
0
.
0
)
m to
the point
𝐵
=
(
2
.
0
,
2
.
0
)
m .

Calculate the work done by
⃑
𝐹
along the path
𝑃
1
.

Calculate the work done by
⃑
𝐹
along the path
𝑃
2
.