Equations of Motion Homework: Acceleration of Block A

In summary, the student is struggling with setting up equations and solving problems. They provide equations for block A and B and question if they are correct. They also question if they should have used a 60° angle instead of 30°.
  • #1
aaronfue
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0

Homework Statement



I seem to be having trouble setting up my equations and not getting the correct answer to some of these problems.

Ex 1:
Determine the acceleration of block A when the system is released. The coefficient of friction and the weight of each block are indicated in the figure. Neglect the mass of the pulleys and cords. See attached image.

Homework Equations



m = [itex]\frac{lb}{32.2}[/itex]

So for my first set of equations on block A:
ƩFx = 2T+ μmgcos60° - mgsin60° = ([itex]\frac{lb}{32.2}[/itex])aA

ƩFy = N - mgcos60° = 0
N = mgcos60°

Ff = μ*N = μmgcos60°

Block B:
+[itex]\uparrow[/itex]
ƩFy = T - mg = ([itex]\frac{lb}{32.2}[/itex])aB

Pulley:
aB = -2aA

1. Are my equations correct?
2. Was I correct to use 60°? (I'm sure it is right but...I feel a bit doubtful.)
 

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  • #2
Look at the picture. The angle is 30°.

ehild
 

FAQ: Equations of Motion Homework: Acceleration of Block A

What is the equation for acceleration?

The equation for acceleration is a = (vf - vi) / t, where a is acceleration, vf is final velocity, vi is initial velocity, and t is time.

How do you calculate the acceleration of an object?

To calculate acceleration, you need to know the change in velocity and the time it took for that change to occur. You can use the equation a = (vf - vi) / t, or you can use the slope of a velocity vs. time graph.

How do you solve for acceleration in an equation of motion problem?

In an equation of motion problem, you need to identify the known variables and plug them into the appropriate equation. If you have the initial and final velocities and the time, you can use the equation a = (vf - vi) / t. If you have the initial velocity, acceleration, and time, you can use the equation vf = vi + at.

What is the difference between average acceleration and instantaneous acceleration?

Average acceleration is the overall change in velocity over a given time period, while instantaneous acceleration is the acceleration at a specific moment in time. Average acceleration is calculated using the change in velocity over the entire time period, while instantaneous acceleration is calculated using the slope of the velocity vs. time graph at a specific point.

How can I use equations of motion to solve real-world problems?

Equations of motion can be applied to real-world problems involving the motion of objects. By identifying the known variables and using the appropriate equation, you can calculate the unknown variables such as acceleration, velocity, or time. This can help in predicting the motion of objects and understanding the forces acting on them.

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