Answer:
-6327.45 Joules
650.375 Joules
378.47166 N
Explanation:
h = Height the bear slides from = 15 m
m = Mass of bear = 43 kg
g = Acceleration due to gravity = 9.81 m/s²
v = Velocity of bear = 5.5 m/s
f = Frictional force
Potential energy is given by
[tex]P=mgh\\\Rightarrow P=43\times -9.81\times 15\\\Rightarrow P=-6327.45\ J[/tex]
Change that occurs in the gravitational potential energy of the bear-Earth system during the slide is -6327.45 Joules
Kinetic energy is given by
[tex]K=\frac{1}{2}mv^2\\\Rightarrow K=\frac{1}{2}\times 43\times 5.5^2\\\Rightarrow K=650.375\ J[/tex]
Kinetic energy of the bear just before hitting the ground is 650.375 Joules
Change in total energy is given by
[tex]\Delta E=fh=-(\Delta K+\Delta P)\\\Rightarrow fh=-(650.375-6327.45)\\\Rightarrow fh=5677.075\\\Rightarrow f=\frac{5677.075}{h}\\\Rightarrow f=\frac{5677.075}{15}\\\Rightarrow f=378.47166\ N[/tex]
The frictional force that acts on the sliding bear is 378.47166 N
Answer
mass of bear = 43 Kg
length of the pine tree = 15 m
speed = 5.5 m/s
a) P.E = m g h
P.E = 43 x 9.8 x 15
P. E = 6321 J
b) [tex]K.E = \dfrac{1}{2} mv^2[/tex]
[tex]K.E = \dfrac{1}{2}\times 43 \times 5.5^2[/tex]
[tex]K.E = 650.375\ J[/tex]
c) average frictional force
K E = P E + energy loss due to friction
650.375 = 6321 + E_f
E_f = -5670.625 J
E_f = F x
-5670.625 = F x 15
F = -378.042 N
