A ball is hanging from a long string that is tied to the ceiling of a train car

Question

A ball is hanging from a long string that is tied to the ceiling of a train car traveling eastward on horizontal tracks. An observer inside the train car sees the ball hang motionless.

Draw a clearly labeled free-body diagram for the ball if the train is speeding up uniformly.
Draw the force vectors with their tails at the dot. The location and orientation of your vectors will be graded. The exact length of your vectors will not be graded but the relative length of one to the other will be graded. The black vector is the sum of the vectors in your diagram.

I am not sure how to do this. I would really appreciate some help on learning the steps for this.

Explanation / Answer

for the first part: the ball and the train are moving at the same speed so the Tension Vector should start at the center and go straight up, the weight of the ball vector should go straight down. Try to make the vectors exactly the same length because the net force equals zero. the second part: i'll get back to you when i solve it..i'm not completely sure but the net force does NOT equal zero! Okay. for the second part.. the tension vector should be 45 deg from the x axis so it should point NE and have a slightly larger length than the weight of the ball. The weight of the ball Vector should still point down and be the same magnitude. Hope this helps

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