The figure below shows a cold package of hot dogs sliding rightward across a fri
ID: 1396085 • Letter: T
Question
The figure below shows a cold package of hot dogs sliding rightward across a frictionless floor through a distance d = 23.0 cm while three forces act on the package. Two of them are horizontal and have the magnitudes F1 = 5.00 N and F2 = 1.00 N; the third force is angled down by = 70.0° and has the magnitude F3 = 4.00 N.
(a) For the 23.0 cm displacement, what is the net work done on the package by the three applied forces, the gravitational force on the package, and the normal force on the package?
J
(b) If the package has a mass of 1.3 kg and an initial kinetic energy of 0, what is its speed at the end of the displacement?
m/s
Explanation / Answer
F1 = + 5 i
F2 = - 1i
F3 = 4*cos70i - 4*sin70 j
Fnet = F1 + F2 + F3
Fnet = 5i - 1i + 4*cos70 i - 4*sin70j
Fnet = 5.37i - 3.76 j
displacement = s = 0.23i
work = dot produt of Fnet*s
W = Fnet . S
W = (5.37i - 3.76 j).(0.23i)
W = 1.2351 J <----answer
+++++++++++++
part(b)
let v be the speed after travelling d distance
final Kinetic energy = KEf = 0.5*m*v^2
from work energy theorem
total work done = change in KE
W = KEf - KEi
W = KEf - 0
W = KEf
1.2351 = 0.5*1.3*v^2
v = 1.38 m/s <------answer
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