- #1
Koscher
- 22
- 0
Homework Statement
Three objects with masses m1 = 37.5 kg, m2 = 19.5 kg, and m3 = 11.1 kg are hanging from ropes that are redirected over pulleys. What is the acceleration of m1? Negative numbers for downward, and positive numbers for upward, please.
There should be a diagram of what the system looks like attached.The attempt at a solution
First I drew a FBD of each of the three masses. I made the tension between mass 2 and 1, the variable T12. I made the tension between mass 1 and 3, the variable T13, just for simplicity sake.
So the equations I got from the FBD were:
T12=m2a+m2g
T13=m3a+m3g
m1g-(T12+T13) =m1a
Then I plugged in the two tension formulas and simply solved for a, which gave me 0.9939 m/s2.
I got the question wrong. What I am really wondering is if it just a wrong sign, and the answer is actually -0.9939 m/s2. Or is there a mistake in the math somewhere that I can not see.
Three objects with masses m1 = 37.5 kg, m2 = 19.5 kg, and m3 = 11.1 kg are hanging from ropes that are redirected over pulleys. What is the acceleration of m1? Negative numbers for downward, and positive numbers for upward, please.
There should be a diagram of what the system looks like attached.The attempt at a solution
First I drew a FBD of each of the three masses. I made the tension between mass 2 and 1, the variable T12. I made the tension between mass 1 and 3, the variable T13, just for simplicity sake.
So the equations I got from the FBD were:
T12=m2a+m2g
T13=m3a+m3g
m1g-(T12+T13) =m1a
Then I plugged in the two tension formulas and simply solved for a, which gave me 0.9939 m/s2.
I got the question wrong. What I am really wondering is if it just a wrong sign, and the answer is actually -0.9939 m/s2. Or is there a mistake in the math somewhere that I can not see.