Block Sliding, might use work energy theorum

AI Thread Summary
To find the acceleration of a 4.2 kg block sliding on a horizontal surface with an initial velocity of 3.3 m/s and a constant friction force of 10.2 N, Newton's Second Law is the most straightforward approach. The discussion highlights that using the work-energy theorem may complicate the problem unnecessarily, as it could lead to a second-order differential equation. Instead, applying the formula F = ma directly simplifies the calculation. The friction force should be equated to the mass times acceleration to find the correct acceleration value. This method is more efficient and avoids potential errors in complex calculations.
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Homework Statement


A block of mass 4.2 kg which has an initial velocity of 3.3 m/s at time t=0, slides on a horizontal surface.

If a constant friction force of 10.2N is exerted on the block by the surface, what is the acceleration?

Homework Equations



Work Energy Theorum?
.5 m vo2 - .5 m v22

v = vo + at



The Attempt at a Solution


I found the kinetic energy of the block, then subtracted the 10.2N of friction. Then I solved for the second velocity. I plugged this into the acceleration equasion, but the answer was not correct? Can anyone help me?
 
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You might be over-thinking this one. What is Newton's Second Law?
 
Using the work energy stuff is going to give you a second order differential equation with 2 boundary conditions to solve (initial and final velocity)
Which is probably a bit harder than is required for this problem..

There is however an equation which relates force to acceleration in a very simple way
 

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