Finding Net Torque in Cable Car Turnaround

• cavery4
In summary, the conversation discusses a problem involving rotating a cable car in San Francisco using a turntable and two people pushing on the car. The question asks for the net torque applied to the car, which can be found by multiplying the force applied by the radius of the turntable. The conversation also mentions confusion about the use of "one-half of a revolution" in the problem, but it is determined that this refers to a rotation of 180 degrees.
cavery4
I don't always pick up on little things in problems. In this particular problem, I am unsure of how to draw the picture when the car is rotated.
Here is the problem:

In San Francisco a very simple technique is used to turn around a cable car when it reaches the end of its route. The car rolls onto a turntable, which can rotate about a vertical axis through its center. Then, two people push perpendicularly on the car, one at each end, as in the drawing. The turntable is rotated one-half of a revolution to turn the car around. If the length of the car is 8.20 m and each person pushes with a 195-N force, what is the net torque applied to the car? (Use the randomzed force given in red above for your calculations, not the 185 N force labeled in the figure.)

http://www.webassign.net/CJ/09_04.gif (That is the picture)

I am confused about how to use the "one-half of a revolution turn" into the problem. I know that one revolution is 360 degrees, and a half is 180 degrees. Am I correct in making that statement based on the one-half of a revolution turn statement?

That sounds like a correct assumption to me. Anyway, I think you'll want to find the radius of the circle, and the torque will just be FxR

do you mean radius = 8.20 / 2 = 4.1
and then 195 * 4.1? I did that and got a wrong answer. I think I am missing something that you are trying to tell me.

Net torque.. so do I have to add those two forces * the radius?

okay. dur. i got it.

1. How is net torque calculated in a cable car turnaround?

Net torque is calculated by multiplying the mass of the cable car by the radius of the turnaround and the acceleration due to gravity. This can be represented by the equation: Net Torque = mass x radius x acceleration due to gravity.

2. What factors affect the net torque in a cable car turnaround?

The factors that affect the net torque in a cable car turnaround include the mass of the cable car, the radius of the turnaround, the angle of the cable, and the acceleration due to gravity. Other factors such as friction and air resistance may also play a role.

3. How does the angle of the cable affect the net torque in a cable car turnaround?

The angle of the cable can greatly affect the net torque in a cable car turnaround. If the cable is at a steeper angle, the net torque will be greater as it will have a larger lever arm. This means that the cable car will experience more rotational force and may turn more quickly.

4. What is the relationship between net torque and rotational equilibrium in a cable car turnaround?

In order for a cable car to maintain rotational equilibrium in a turnaround, the net torque must be equal to zero. This means that the clockwise and counterclockwise torques must be balanced. If the net torque is not equal to zero, the cable car will experience rotation and may not remain in equilibrium.

5. Can the net torque in a cable car turnaround be negative?

Yes, the net torque in a cable car turnaround can be negative. This would occur if the counterclockwise torque is greater than the clockwise torque. This can result in the cable car rotating in the opposite direction or slowing down in its rotation.

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