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alex12342011
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1.
Homework Statement
See attachment please
Mass block 1= 20kg
Mass block 2= 30kg
Incline block 1= 40 degrees
Incline block 2= 60 degrees
Coefficient of kinetic friction block 1= 0.20
Coefficient of kinetic friction block 2= 0.30
Acceleration due to gravity= 9.81m/s^2Determine the acceleration and the tension n the rope. Assume pulley is mass less/frictionless and the rope is mass less.
F=m*a
Ffriction= coefficient*Fnormal
Drew fbd for each block
Found weight of each block using F=ma
Block 1 Fg= 196N
Block 2 Fg= 294N
Split them into components
Block 1
Fgx= 196sin40=126N
Fgy= 196cos40=150N
Block 2
Fgx= 294sin60=255N
Fgy=294cos60=147N
Fnormal = Fgy
Block1 Ffriction= 0.2(150)= 30N
Block2 Ffricion= 0.3(147)=44N
I am not sure which way it will accelerate. At first I thought it would accelerate to the right, however the answer says otherwise. To find which way it accelerates, I thought I would solve for the frictional force and the x component of gravity for each block. Then
compare them to see which is greater (I pretend as if there was no rope/force of tension)
Is this the correct way of finding what way it accelerates?
The answer told me it would accelerate left, so I continued knowing this and set my x axis
to make the acceleration in the x-axis positive.
Block 1 (20kg)
Net force= Fgx-Ffriction-Ftension
Net force= 126-30-Ftension
Net force= m*a
20a=126-30-Ftension
20a=96-Ftension
Ftension=96-20a
Block 2 (30kg)
Net force= Ftension-Fgx-Ffriction
Net force= Ftension-255-44
Net force= m*a
30a=Ftension-255-44
30a=Ftension-211
Ftension=30a+211
So now I set them equal to each other to find the acceleration?
96-20a=30a+211
-20a-30a=211-96
-50a=115
a=-2.3m/s^2
But this answer is not right? I am very confused. Any help is appreciated thanks!
Answer:
Acceleration= 1.1m/s^2 left
Force of tension= 180N
Homework Statement
See attachment please
Mass block 1= 20kg
Mass block 2= 30kg
Incline block 1= 40 degrees
Incline block 2= 60 degrees
Coefficient of kinetic friction block 1= 0.20
Coefficient of kinetic friction block 2= 0.30
Acceleration due to gravity= 9.81m/s^2Determine the acceleration and the tension n the rope. Assume pulley is mass less/frictionless and the rope is mass less.
Homework Equations
F=m*a
Ffriction= coefficient*Fnormal
The Attempt at a Solution
Drew fbd for each block
Found weight of each block using F=ma
Block 1 Fg= 196N
Block 2 Fg= 294N
Split them into components
Block 1
Fgx= 196sin40=126N
Fgy= 196cos40=150N
Block 2
Fgx= 294sin60=255N
Fgy=294cos60=147N
Fnormal = Fgy
Block1 Ffriction= 0.2(150)= 30N
Block2 Ffricion= 0.3(147)=44N
I am not sure which way it will accelerate. At first I thought it would accelerate to the right, however the answer says otherwise. To find which way it accelerates, I thought I would solve for the frictional force and the x component of gravity for each block. Then
compare them to see which is greater (I pretend as if there was no rope/force of tension)
Is this the correct way of finding what way it accelerates?
The answer told me it would accelerate left, so I continued knowing this and set my x axis
to make the acceleration in the x-axis positive.
Block 1 (20kg)
Net force= Fgx-Ffriction-Ftension
Net force= 126-30-Ftension
Net force= m*a
20a=126-30-Ftension
20a=96-Ftension
Ftension=96-20a
Block 2 (30kg)
Net force= Ftension-Fgx-Ffriction
Net force= Ftension-255-44
Net force= m*a
30a=Ftension-255-44
30a=Ftension-211
Ftension=30a+211
So now I set them equal to each other to find the acceleration?
96-20a=30a+211
-20a-30a=211-96
-50a=115
a=-2.3m/s^2
But this answer is not right? I am very confused. Any help is appreciated thanks!
Answer:
Acceleration= 1.1m/s^2 left
Force of tension= 180N
Attachments
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