A cart is motionless on a horizontal track. The front of the car is faced towards the left, and the back is faced towards the right. Attached to the back of the car is a string with a mass. A hand is is holding the front of the car, preventing it from moving to the right. When the hand is released, the car accelerates towards the right. A motion sensor is on one side of the track.
http://w3.rcnuwc.no/public/physics/test/ict%20website-2-/Images/Practicals%20images/prac2diag.gif

When you look at the Force vs. Time graph, the line ''steps'' down when the hand is released. Why does this occur

Question

A cart is motionless on a horizontal track. The front of the car is faced towards the left, and the back is faced towards the right. Attached to the back of the car is a string with a mass. A hand is is holding the front of the car, preventing it from moving to the right. When the hand is released, the car accelerates towards the right. A motion sensor is on one side of the track. 
http://w3.rcnuwc.no/public/physics/test/ict%20website-2-/Images/Practicals%20images/prac2diag.gif

When you look at the Force vs. Time graph, the line ''steps'' down when the hand is released. Why does this occur

anonymous · Answer

Sorry, I forgot the question mark at the end. Attached to this message is the Force vs Time graph for the cart. If you have any questions or need more details, please let me know I will be happy to provide them for you. Any help is appreciated. Thank you!  :D

anonymous · Answer

I will refer this problem to @ganeshie8, since I believe he can help me.   :)

anonymous · Answer

@TheSmartOne, could you take look at this problem? Thank you very much.   :D

pawanyadav · Answer

When can is at rest hand are applying force on it let say at t=0
 But after some time the cat start move to right means hands are applying less force on car than required which shows decrement of force with time

pawanyadav · Answer

So line in force vs time graph "steps" down.

anonymous · Answer

@Pawanyadav, well, the hands are removed COMPLETELY after 1 or 2 seconds. It is not gradual, but an instant process. When the motion sensor starts recording time and collecting data, the person holding the cart takes 1 or 2 seconds to react. After that, he/she instantly removes their hand. Immediately, the force ''steps down'' on the graph. I don't think it's because of a removal of the hand itself. It could be something caused by the removal of the hand.   :D

anonymous · Answer

@pooja195, would you like to take a look at this problem?   :D

anonymous · Answer

@Astrophysic, could you help me with this problem? I would appreciate it a lot.   :D

anonymous · Answer

@Astrophysics and @Nnesha, would you like to help me solve this?   :)

anonymous · Answer

@Preetha, do you think you can help me with this problem?   :D