Frictionless pulley problem

In summary, the problem involves a 1.0 kg tin of anti-oxidants on an incline connected to a 2.0 kg tin of corned beef through a massless and frictionless pulley. An upward force of 6.0 N is applied to the corned beef tin, causing it to have a downward acceleration of 5.5 m/s2. The task is to find the tension in the connecting cord and the angle of the incline. Using the equations of motion, the tension can be solved for by setting the acceleration of both masses equal and the angle can be solved for by adding the two equations. The solution also considers the upward force acting on the hanging mass.
  • #1
SnowOwl18
71
0
I'm trying to help a friend with this problem and we are both very stuck. I wanted to ask for help here for him.

-------A 1.0 kg tin of anti-oxidants on a frictionless inclined surface is
connected to a 2.0 kg tin of corned beef. The pulley is massless and frictionless. An
upward force F r of 6.0 N acts on the corned beef tin, which has a downward acceleration
of 5.5 m/s2. (a) What is the tension in the connecting cord? (b) What is the angle b ?--------

Unfortunately, I can't post the picture of the problem...but basically there is one tin (anti-oxidants) on an incline and attached to it is a cord that goes through a pulley...and on the other end of the cord, hanging straight down is the other tin (corned beef). The angle, b, is the angle of the incline, i think. I found an equation that might work for finding the tension. T= [(m1m2(1+sintheta))/ m1 + m2]g . But the problem is we don't know the angle or how to find it. If anyone could please help us out, we'd greatly appreciate it.
 
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  • #2
Firstly, your answer for T does not include the upward force Fr acting on the hanging mass. Hence it is incomplete.

In my solution below, [tex]m_{1}[/tex] denotes the mass on the incline and [tex]m_{2}[/tex] denotes the hanging mass

The equations of motion are:

[tex]T - m_{1}g\sin\alpha = m_{1}a[/tex] (for the mass on the incline)
[tex]m_{2}g - T - F_{r}= m_{2}a[/tex] (for the hanging mass)

Adding these two equations, you get

[tex]m_{2}g - m_{1}g\sin\alpha - F_{r}= (m_{1}+m_{2})a[/tex]

You can see for yourself that both the masses are constrained to move with the same (magnitudinally) acceleration for the rope to remain taut. The acceleration is given to you so you can go ahead and solve for the angle alpha from this equation. From the second equation, you can solve for T.

Hope that helps.

Cheers
Vivek
(I hope I've understood your question correctly)
 
  • #3
Thanks so much! :eek:)
 

1. What is a frictionless pulley problem?

A frictionless pulley problem refers to a physics scenario in which a pulley is assumed to have no friction or resistance, resulting in simplified equations and calculations.

2. How is a frictionless pulley problem different from a regular pulley problem?

In a regular pulley problem, friction and resistance are taken into account, making the equations and calculations more complex. In a frictionless pulley problem, these factors are ignored, resulting in a simpler scenario to analyze.

3. Why are frictionless pulley problems used in physics?

Frictionless pulley problems are used in physics to simplify the analysis of pulley systems and to better understand the principles of mechanics and motion. They also serve as a building block for more complex scenarios that involve pulleys.

4. What are some real-life examples of frictionless pulley problems?

Some real-life examples of frictionless pulley problems include flagpoles, cranes, and elevators. In these scenarios, the pulleys are assumed to have no friction, making the calculations simpler.

5. How do you solve a frictionless pulley problem?

To solve a frictionless pulley problem, you can use the principle of conservation of energy or Newton's laws of motion. It involves identifying the forces acting on the system and using the appropriate equations to calculate the unknown variables.

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