Answer:
[tex]a = 0.65\ m/s^2[/tex]
Explanation:
Net Force
There are four forces acting on the sled:
Its weight W directed down
The normal force N directed up
The applied force F directed left
The friction force, opposite to the motion, directed right.
The forces are shown in the free-body diagram of the figure below.
The body is in equilibrium in the vertical direction, thus:
N = W = m.g
N = 80 Kg . 9.8 [tex]m/s^2[/tex]
N = 784 Nw
In the horizontal direction, the sum of the force vectors is the net force:
Fn = F-Fr
It's assumed the left as positive.
The friction force is calculated as:
[tex]Fr =\mu_k . N[/tex]
Fr =0.125*784 Nw
Fr = 98 Nw
According to Newton's second law, the net force is equal to the mass by the acceleration:
F-Fr=m.a
The acceleration can be calculated by solving for a:
[tex]\displaystyle a=\frac{F-Fr}{m}[/tex]
[tex]\displaystyle a=\frac{150-98}{80}[/tex]
[tex]\mathbf{a = 0.65\ m/s^2}[/tex]
