Answer to Question #250053 in Classical Mechanics for Jacobo

Question

A block is pulled to the right with a force of 250 N forming an angle of 42º, applying this force, the block reaches an acceleration of 1.5m / s.

The coefficient of friction is 0.3

a) Calculate the mass of the block.

b) Determine the normal force and the friction force

Answer 1

a)

$F_{fr}=\mu N=\mu mg,$

$F\cos\alpha-F_{fr}=ma,$

$m=\frac{F\cos\alpha}{\mu g+a}=42~\text{kg},$

b)

$N=mg=412~\text N,$

$F_{fr}=\mu N=124~\text N.$