- #1
ja!mee
- 16
- 0
Okay So, the question I have here is..
Masses are connected as shown. m1 = 5.0 kg and m2 = 4.0 kg.
a) find the acceleration of each object and
b) the tension in the two strings
I have attached the picture example as well (as there is another unlisted weight in it) With pulley problem's I find it easier to find the acceleration first, so I have done so with:
a = Fg7- Fg5/Mt
a = (7kg)(9.8 m/s2) - (5kg)(9.8 m/s2) / 12 kg
where Fg7 is the force of gravity on the 4kg an 3 kg weigh combined and Fg5 is the force of gravity with the 5 kg weight.
I have found the the correct answer for question A) which is acceleration = 1.63
Now with that said an done I am not looking for the rope tension, I have my equation:
T = Fg7 - ma
T = 7 kg (9.8 + 1.6)
T = 79.8 N
Well that's all fine and dandy, but I am in a course where the answers are provided, it is the work that you do to get to the answer that really counts. The answer I have provided is not 79.8 N but 57N.
The only way I could see getting to this answer is
T = Fg5 - ma
T = 5 kg (9.8 + 1.6)
T = 57 N
It is my understanding that the tension equation that I take should come from the heaviest set of weights on any given side of the pulley. From the picture provided, you can see that there are two sets of weights on the one side of the pulley. Am I wrong in thinking that to find the tension I should add those two weights together and find the Tension from that number? Because this seems to contradict what the answer I have been provided is saying.
Or am I missing something completely?
Masses are connected as shown. m1 = 5.0 kg and m2 = 4.0 kg.
a) find the acceleration of each object and
b) the tension in the two strings
I have attached the picture example as well (as there is another unlisted weight in it) With pulley problem's I find it easier to find the acceleration first, so I have done so with:
a = Fg7- Fg5/Mt
a = (7kg)(9.8 m/s2) - (5kg)(9.8 m/s2) / 12 kg
where Fg7 is the force of gravity on the 4kg an 3 kg weigh combined and Fg5 is the force of gravity with the 5 kg weight.
I have found the the correct answer for question A) which is acceleration = 1.63
Now with that said an done I am not looking for the rope tension, I have my equation:
T = Fg7 - ma
T = 7 kg (9.8 + 1.6)
T = 79.8 N
Well that's all fine and dandy, but I am in a course where the answers are provided, it is the work that you do to get to the answer that really counts. The answer I have provided is not 79.8 N but 57N.
The only way I could see getting to this answer is
T = Fg5 - ma
T = 5 kg (9.8 + 1.6)
T = 57 N
It is my understanding that the tension equation that I take should come from the heaviest set of weights on any given side of the pulley. From the picture provided, you can see that there are two sets of weights on the one side of the pulley. Am I wrong in thinking that to find the tension I should add those two weights together and find the Tension from that number? Because this seems to contradict what the answer I have been provided is saying.
Or am I missing something completely?