Ok, I am stumped by this question:
In the system in the diagram below, block M (15.7 kg) is initially moving to the left. A force F , with magnitude 60.5 N, acts on it directed at an angle of 35.0 degrees above the horizontal as shown. The mass m is 8.2 kg. There is no friction and the pulley and string are massless.
- What is the normal force (N) on M ?
- What is the tension (N) in the string?
- What is the acceleration (m/s2) of M (positive is to the right)?
I tried and got the following:
Got the X component of the force F: F * Cos (35) = 49.55869868 N
Got the Y component of the force F: F * Sin (35) = 34.7013744 N
Got the force of m on M: 8.2 * 9.8 = 80.36 N (which is what I assumed the tension on the string was)
I got the acceleration of M caused by m = -5.118471338
Then I got the acceleration of M cause by F = 3.156605011
Putting it all together I got the following answers:
- 129 N
- 80.4 N
- -1.96 m/s^2
I (obviously) got all three wrong. The correct answers are:
- 119 N
- 69.8 N
- -1.29 m/s^2
So, I'm stuck. There is something missing that is causing my string tension to be off. If I would have gotten the right string tension, all the other answers would have been correct. I know that is where the problem is, so if someone could point out my mistake, that would be wonderful!