Finding tension on multiple points.

[squalami]

1. A 1.0-m-long massive steel cable drags a 20 kg block across a horizontal, frictionless surface. A 100 N force applied to the cable causes the block to travel 4.0 m in 2.0 s.Graph the tension in the cable as a function of position along the cable, starting at the point where the cable is attached to the block.

2. F = T = ma

3. i was taught that if you have a frictionless surface that the tension in a rope will be the same throughout the rope but i keep getting a wrong answer. . .

 

[rl.bhat]

Hi squalami welcome to PF.
In the problem, the displacement and time is given. Find acceleration a of the block and the cable.
Find the force F required to move the block using m*a. This force is less than 100 N.
Find the difference (100 - F). That is force required to move the cable. From that find the mass of the cable. Then proceed like connected mass type problem.

 

[tomcue]

I would like to first point out that the given information is incomplete. We would need to know the angle at which the cable is being pulled, as well as the coefficient of friction of the surface, in order to accurately calculate the tension at different points along the cable.

However, assuming that the cable is being pulled at a constant angle and the surface is truly frictionless, we can use the equation F = T = ma to calculate the tension at different points along the cable. This equation states that the force (F) applied to an object is equal to the mass (m) of the object times its acceleration (a). In this case, the object is the 20 kg block and the acceleration is the change in its velocity over time (4.0 m/2.0 s = 2.0 m/s^2).

Using this equation, we can calculate the tension at the point where the cable is attached to the block (T1). This would be equal to the force applied (100 N) minus the force required to accelerate the block (20 kg x 2.0 m/s^2 = 40 N). Therefore, the tension at this point would be 60 N.

As for the tension at other points along the cable, it would depend on the angle at which the cable is being pulled. If the angle is constant, then the tension should also be constant throughout the cable. However, if the angle changes, then the tension at different points along the cable would also change.

In conclusion, without complete information, it is difficult to accurately graph the tension in the cable as a function of position. However, using the given information and the equation F = T = ma, we can calculate the tension at the point where the cable is attached to the block and determine that the tension should be constant throughout the cable if the angle is constant.