Answer:t=0.81 s
Explanation:
Given
Penguin slides down with constant velocity of 3.57 m/s
as the Penguin Slides with constant velocity therefore [tex]F_{net}[/tex] is zero on Penguin
[tex]F_{net}=mg\sin \theta -f_r[/tex]
[tex]f_r=[/tex]friction Force
[tex]f_r=\mu mg[/tex]
[tex]\mu =[/tex]coefficient of Kinetic friction
[tex]mg\sin \theta =\mu mg[/tex]
[tex]\tan \theta =\mu [/tex]
[tex]\mu =\tan 9.85=0.45[/tex]
after reaching on floor final velocity of penguin will be zero after time t
thus
[tex]v=u+at[/tex]
here [tex]a=\mu g[/tex]
[tex]a=0.45\times 9.8=4.41[/tex] (deceleration)
[tex]0=3.57-4.41\times t[/tex]
[tex]t=\frac{3.57}{4.41}=0.809[/tex]
[tex]t=0.81 s[/tex]