# Post Lab Question

by Habibrobert
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 P: 7 Hello everyone, I'm working on a physics postlab due tomorrow, and I'm just really skeptical that the answers I am getting so far are correct, I just feel like the problems are designed to "trick you" because of the values you are looking for are on the graph. could you guys please take a look at it and tell me how to do this particular page of the prelab correctly? The set up is a cart on a frictionless track that has a string tied to it which is also tied to some weight (the prelab calls it a hanger) that is hanging down and pulling on the cart. Attached a screen shot of the prelab Thanks very much! Attached Thumbnails
 Mentor P: 11,928 Check the decimal point for the force. Where is that force measured? How did you get the mass of the hanger?
 P: 7 The force is measured from the car, before and after it was released. I used F=m*a to find the mass of the hanger, but I feel like that is wrong.
Mentor
P: 11,928
Post Lab Question

 Quote by Habibrobert The force is measured from the car, before and after it was released.
In other words, it is the tension of the string connecting both?

 I used F=m*a to find the mass of the hanger, but I feel like that is wrong.
It is hard to tell if you don't add which a and F you used. The mass looks wrong.
 P: 358 Is the force sensor mounted on the cart and the string tied to the force sensor?Accleration ok. Decimal point in force on force sensor while accelrating wrong. I am not sure if they want the negative though. All it means is that the force sensor is registering a pull , which is displayed as a negative value. A push on the sensor will be displayed as a positive value. Mass of the hanger wrong. The force sensor reads the (full) tension in the string when the cart is stationary.

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