A force problem that seems easy but hard

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In summary, the conversation discusses the acceleration and tension in a system consisting of a 2.00-kg aluminum block and a 6.00-kg copper block connected by a light string over a frictionless pulley. Using Table 4.2, the acceleration of the blocks cannot be determined due to the lack of enough equations. The tension in the string can be found by resolving the forces in the x-direction for the copper block and using the fact that both blocks have equal accelerations and tensions. The y-direction does not need to be considered as there is no acceleration in that direction for either block.
  • #1
cy19861126
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A 2.00-kg aluminum block and a 6.00-kg copper block are connected by a light string over a frictionless pulley. The two blocks are allowed to move on a fixed steel block wedge (of angle 30.0) as shown in Figure P4.53. Making use of Table 4.2, determine (a) the acceleration of the two blocks and (b) the tension in the string.

My work so far:
For the aluminum block - I got T = 2a, which I cannot solve
For the copper block - I got Tx-58.8sin(30) = 6a - this is for x direction
and
Ny-58.8cos(30) = 6a - this is for y direction

58.8 is the weight force, which comes from 6*9.8 = 58.8N
T = tension force
N = Normal force

All the equations won't get me to solve for acceleration for either blocks

Thanks~~

If you cannot see the attachment, you may click http://students.washington.edu/cy1126/P4.53.jpg"
 

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  • #2
You don't need an x for the direction of T for the copper block since you are resolving it along the surface of the plane. Once you get this, its semple simultaneous equations.
 
  • #3
QuantumCrash said:
You don't need an x for the direction of T for the copper block since you are resolving it along the surface of the plane. Once you get this, its semple simultaneous equations.
I see what you are saying, but for the copper block, I defined the x-axis to be the the ramp. Therefore, the coordinate diagram is a slanted one, not a standard one. As a result, you need Tx
 
  • #4
Neither block is accelerating in the y as you have defined it. Tension is purely in the x. You then get 2 equations with 2 unknowns because the tensions and accelerations are equal
 
  • #5
If I get what you mean, you should not do that becaus you would need to take into account the normal force.
 

Related to A force problem that seems easy but hard

1. What is the force?

The force is a physical quantity that causes an object to accelerate. It is measured in units of Newtons (N) and is represented by the symbol F.

2. How is force calculated?

Force is calculated by multiplying mass by acceleration, using the equation F = ma. This means that the greater the mass or acceleration of an object, the greater the force acting on it.

3. What is the difference between mass and weight?

Mass is a measure of the amount of matter in an object, while weight is a measure of the force of gravity acting on an object. Mass is constant, while weight can change depending on the strength of gravity in a given location.

4. What are some common units of force?

The most commonly used unit of force is the Newton (N), but other units such as pounds (lb) and kilograms (kg) are also used. In some cases, force may also be measured in terms of energy, such as joules (J) or calories (cal).

5. How can I solve a difficult force problem?

To solve a difficult force problem, it is important to break it down into smaller, more manageable parts. Identify the known and unknown values, and use equations and principles of physics to solve for the unknowns. It may also be helpful to draw diagrams or use real-world examples to better understand and visualize the problem.

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