Question

What force is needed to keeps 20kg box moving at a constant velocity when the mk is 0.3021 and the force is a push at 20 degree to the ground

Answer 1

Answer:

63.0 N

Explanation:

According to Newton's second law, the resultant of the forces acting along the horizontal direction is equal to the product of mass and acceleration:

$F_{net}=ma$ (1)

The box is moving at constant velocity, so the acceleration is zero: a=0, and so the net force is also zero.

The net force consists of two forces:

- The horizontal component of the push, given by:

$F_x = F cos \theta$

where $\theta=20^{\circ}$

- The frictional force, acting in the opposite direction of the push:

$F_f = \mu mg$

where $\mu=0.3021$ is the coefficient of friction, m=20 kg is the mass of the box and g=9.8 m/s^2.

Therefore, eq.(1) becomes

$F_x - F_f =0\\F cos \theta - \mu mg =0$

From which we find the push, F:

$F=\frac{\mu mg}{cos \theta}=\frac{(0.3021)(20 kg)(9.8 m/s^2)}{cos 20^{\circ}}=63.0 N$