How do I calculate the mass of a moving object?

AI Thread Summary
To calculate the mass of the couch, the applied force of 350 Newtons at a 30-degree angle must be considered along with the coefficients of friction, where static friction is 0.4 and kinetic friction is 0.3. The force of static friction is calculated as 140 N, which is derived from the equation Fs = μsN. The normal force is expressed as N = mgcosθ, leading to the equation 350 = 0.866mg. The initial attempt at solving the problem contained errors in interpreting forces and equations, indicating a need for careful reevaluation of the calculations. Accurate calculations are essential for determining the couch's mass correctly.
Joseph Hotto

Homework Statement



Someone mistakenly threw away a lovely couch, and you decide to take it back to your apartment. You push it with a force of 350 Newtons and at 30 degrees below the horizontal at 2 m/s. The coefficents of friction are μs = 0.4 and μf = 0.3. What is the couch's mass?

Homework Equations


Fs = μsN
N = mgcosθ
F = ma

The Attempt at a Solution


Fs = (0.4) (350 N)
= 140 N <- Force of static friction
ΣFx = (350) = (2m/s) * M + 2 (0.4) * M - 2(0.3 M)
350N = mg (cos(330 degrees)
350 = 0.866 mg
 
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Reconsider your calculation of the force of friction.
The quantity (2 m/s)*M is not a force. The entire equaiton for ΣFx is incorrect.
 

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