h t t p : / / w w w . j i s k h a . c o m / d i s p l a y . c g i ? i d = 1 2 6 7 3 9 3 5 9 3
ok heres the problem in a picture
h t t p : / / i m g 1 9 2 . i m a g e s h a c k . u s / i m g 1 9 2 / 4 5 0 0 / c a p t u r e x x w . j p g
ok I called the 4 kg block m3 and the 2 kg block m2 and the 1 kg block m1
I don't see what is wrong with my work
a. net force on m3 = m3 a = Fg3 - Fg2 - Fg1
divide by m3 to get a
a = (Fg3 - Fg2 - Fg1)/m3
made it look nice
a = (m3 g - m2 g - m1 g)/m3
= g - (m2g)/m3 - (m1 g)/m3
= g(1 - m2/m3 - m1/m3)
=9.8(1 - 2/4 - 1/4) = 2.5 m/s^2
b. net force on m3 = m3 a = Fg3 - Ft3
solved for the force of tension
Ft3 = -m3(a+g) = -4.0(2.5+9.8)= - 49 N
c. Net force m1 = m1 a = -Fg1 + Ft1
solved for Ft1
Ft1 = m1 (a+g) = 1.0(2.5 + 9.8) = 12 N
what is wrong with your work:
you wrote: a = (m3 g - m2 g - m1 g)/m3
but that means m3*a=net force which is NOT true.
NET FORCE= totalmass*acceleration
total mass is Mass1+Mass2+mass3
you cannot apply net force to just one object.
you should have written:
a = (m3 g - m2 g - m1 g)/(m3+m2+m1)
hmmmmmm thanks
Based on the provided information, it seems like you are working on a physics problem involving three blocks (m1, m2, and m3) and calculating net force and tension forces. You have correctly written down the equations for net force on m3 and m1.
To determine what might be wrong with your work, I will analyze your calculations step by step:
a. Net force on m3:
You correctly wrote: net force on m3 = m3 a = Fg3 - Fg2 - Fg1
This equation represents the sum of all the forces acting on m3.
Next, you divided the equation by m3 to find the acceleration, which is correct:
a = (Fg3 - Fg2 - Fg1)/m3
You then rearranged the equation to make it more readable, and it seems accurate:
a = (m3 g - m2 g - m1 g)/m3
You continued to simplify the equation:
a = g - (m2g)/m3 - (m1 g)/m3
At this point, you made an error in distributing the g to both (m2g)/m3 and (m1 g)/m3. The correct equation should be:
a = g - (m2g + m1g)/m3
Finally, you substituted the given values and calculated the value of acceleration correctly:
a = 9.8(1 - 2/4 - 1/4) = 2.5 m/s^2
b. Net force on m3:
You correctly wrote: net force on m3 = m3 a = Fg3 - Ft3
This equation represents the sum of all the forces acting on m3.
To find the tension force (Ft3), you rearranged the equation correctly:
Ft3 = -m3(a+g) = -4.0(2.5+9.8) = -49 N
c. Net force on m1:
You correctly wrote: net force on m1 = m1 a = -Fg1 + Ft1
This equation represents the sum of all the forces acting on m1.
To find the tension force (Ft1), you rearranged the equation correctly:
Ft1 = m1 (a+g) = 1.0(2.5+9.8) = 12 N
In conclusion, the only error in your calculations is in the simplification step of equation a. The correct equation should be a = g - (m2g + m1g)/m3. Other than that, your work seems fine.