One day finds your physics instructor moving a M1 = 8.0 kg crate of old books. O
ID: 2061905 • Letter: O
Question
One day finds your physics instructor moving a M1 = 8.0 kg crate of
old books. On the way to the recycling bin, he finds a M2 = 6.0 kg
crate of old physics demos, so he places it on top of the first. By
exerting a force, F = 40N at 37 above the horizontal, to the upper
crate, he gets the combination to slide to the right with constant speed.
What is the minimum coefficient of friction between M1 and the floor,
as well as, between the two masses? Assume, as shown, that the crates
remain horizontal and in contact with each other.
Explanation / Answer
in 1st case consider M1 and M2 as a single system
=> horizontal forces acting on the system = Fcos37 and frictional force
=> Fcos37 = f
=> F(4/5) = f
=> f = 4/5 * 40 = 32N
normal force on the system :N
N + F sin37 = (m1+m2)g
=> N = 113.2N
f = N
=> 32 = *113.2
=> = 0.282
case 2
force on mass m2 = Fcos37 = 32N
=>friction force between the two blocks = 32N
Normal force on M1 = M2g = 6*9.8N
=> 32 = *58.5
=> = 0.544 between the two blocks
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.