- #1
blackandyello
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Homework Statement
A factory worker pushes a 30.0-kg crate a distance of 4.5. along a level floor at constant speed by pushing horizontally on it. The coefficient of kinetic friction between the crate and the floor is 0.25. (a) What magnitude of force must the worker apply?
Homework Equations
summation of F x forces = 0
frictional force = coefficient of fric * normal force
The Attempt at a Solution
Hello, my solution is this
since the frictional force and the force of the worker in the x direction are equal,
fric force = 0.25 * 9.8 * 30 kg
fric force = 73.5 NEWTONS
so to find the magnitude of the force that the worker apply, we simply use trigonometric ratios.
cos (30) = 73.5 / r
r = 84.87 Newtons
my answer is 84.87, but the answer in the book is 99.2 Newtons. can you tell me where did i go wrong? tnx