A60 kg crate is dragged across a floor by pulling on a rope attached to the crate and inclined 18° above the horizontal. (a) if the coefficient of static friction is 0.51, what minimum force magnitude is required from the rope to start the crate moving? (b) if μk = 0.26, what is the magnitude of the initial acceleration (m/s^2) of the crate?

Explanation:

Given

mass of crate=60 kg

inclination

Suppose Force applied by rope is F

F=181.70+285.20=466.9 N

(b)=0.26

here

initial speed when it is dropped is 150 ft/s

now at the same moment the acceleration due to gravity is perpendicular to its velocity

so as we know that

now we have centripetal acceleration a = 32 ft/s^2 as its perpendicular to velocity

while tangential acceleration at the same moment will be zero

so

now radius of curvature is given as

so the radius of curvature just after it is dropped is 703.125 ft

snell's law

refractve index = sin incidence / sin refraction