A 1,160-N crate is being pushed across a level floo t speed by a force F of 270
ID: 1884970 • Letter: A
Question
A 1,160-N crate is being pushed across a level floo t speed by a force F of 270 N at an angle of 20.0° below the 20.0 20.0° (a) What is the coefficient of kinetic friction between the crate and the floor? (Enter your answer to at least three decimal places.) (b) If the 270-N force is instead pulling the block at an angle of 20.0° above the horizontal, as shown in the figure b, what will be the acceleration of the crate? Assume that the coefficient of friction is the same as that found in part (a) Read It Show My Work (Optional)Explanation / Answer
here,
weight of crate , W = 1160 N
force , F= 270 N
theta = 20 degree
a)
let the coefficient of kinetic friction be uk
as it is moving at constant speed
the net force is zero
F * cos(theta) = uk * ( W + F * sin(theta))
270 * cos(20) = uk * ( 1160 + 270 * sin(20))
solving for uk
uk = 0.20
b)
the accelration of the system , a = net force /effective mass
a = (F * cos(theta) - uk * ( W - F * sin(theta)) /(W/g)
a = ( 270 * cos(20) - 0.2025 * ( 1160 - 270 * sin(20))) /( 1160/9.81)
a = 0.32 m/s^2
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