(adsbygoogle = window.adsbygoogle || []).push({}); HELP!!!A dynamic question with friction

1. The problem statement, all variables and given/known data

Two blocks lie on a table as shown and are connected by an inextensible cord around a frictionless, massless pulley. A force F=50N is applied to the pulley. The coefficients of friction between the blocks and the table are mu(s)=0.20, and mu(k)=0.10, and the masses are m1=10kg,m2=20kg.

a)determine the accelerations of the blocks and the pulley

b)the applied force is instantaneously increased to F=100N. What are the accelerations now?

c)What are the accelerations if the force drops instantaneously from F=100N to 50N

2. Relevant equations

F(friction)=mu(k) times F(normal)

Acceleration= net horizontal force/total mass

F(normal)=total mass times gravity

net horizontal force= force applied - frictional force

3. The attempt at a solution

a)F(normal)=(10+20)(9.8)=294N

net horizontal force=50N-29.4N=20.6N

Acceleration=20.6/30=0.69m/s^2

b)net horizontal force=100N-29.4N=70.6N

Acceleration=70.6/30=2.35m/s^2

c)I am not really sure how to do this because if the force drops to 50N then isn't it same as the question a). If it is same as the question a) then the answer will be 0.69m/s^2.

Thank you for helping me.

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# Homework Help: HELP A dynamic question with friction

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