A 50.0-kg box is being pushed along a horizontal surface by a force of 250 n directed 28.0o below the horizontal. the coefficient of kinetic friction between the box and the surface is 0.300. what is the acceleration of the box?

Respuesta :

Refer to the figure shown below.

Tha applied force of F = 250 N has 
(i) a horizontal component of  Fx = (250 N) cos(28°) = 220.737 N,
(ii) an upward vertical component of Fy = (250 N) sin(28°) = 117.368 N

The weight of the box is
  W =(50 kg)*(9.8 m/s²) = 490 N
The normal reaction on the box is
 N = W - Fx = 490 - 117.368 = 372.632 N

The resistive frictional force on the box is
μN = 0.3*372.632 = 111.790 N

The horizontal driving force on the box is
Fx - μN = 220.737 - 111.790 = 108.947 N

If the acceleration of the box is a m/s², then
(50 kg)*(a m/s²) = (108.947 N)
a = 108.947/50 = 2.179 m/s²

Answer:
The acceleration of the box is 2.18 m/s² (nearest hundredth)
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