Concept explainers
To evaluate: The acceleration of the two blocks sliding down is to be evaluated.
Answer to Problem 42P
The acceleration of each block is 0.758 m/s2
Explanation of Solution
Introduction:Newton's second law explains that the acceleration of an object is dependent upon two variables. Those are net force acting on the object and the object’s mass.
When the blocks are going down the plane. The frictional force should be upward the plane.
It is known that the component of the gravitational force down the plane is mg cosθ and the
component perpendicular to the plane is mg sin θ as shown in the figure below.
The frictional force acting on the first block is,
Here,
normal force on the first block.
Applying Newton's second law to the first block, the net force along the horizontal direction is
Applying Newton's second law to the first block, the net force along the vertical direction is,
Rewrite the equation for
Substitute
Thus, the tension in the string is,
The frictional force acting on the second block is,
Here,
normal force on the second block.
Applying Newton's second law to the second block, the net force along the horizontal direction is,
Applying Newton's second law to the first block, the net force along the vertical direction is,
Rewrite the equation for FN2.
Substitute
Thus, the tension in the string is,
Compare the equations of tensions, we get
Thus, the magnitude of the common acceleration of the two blocks is as follows.
Substitute 9.8 m/s2 for g, 1.0 for µ1, 1.0 kg for m1, 2.0 kg for m2, 30.0° for θ, and 0.50 for µ2,
Therefore, the acceleration of each block is 0.758 m/s2
Conclusion: By using Newton's second law acceleration can be determined.
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Chapter 5 Solutions
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