Runner whose weight is 800 N wishes to accelerate at 5m/s^2 what minimum coefficient of friction is required for her to accelerate without slipping?
A)0.25
B)0.50
C)0.30
D)0.40

B) 0.50

Explanation:

Draw a free body diagram.  There are three forces: weight force mg down, normal force N up, and friction force Nμ forward.

Sum of forces in the y direction:

∑F = ma

N − mg = 0

N = mg

Sum of forces in the x direction:

∑F = ma

Nμ = ma

mgμ = ma

gμ = a

μ = a / g

μ = (5 m/s²) / (10 m/s²)

μ = 0.50

+15-35=-20

going in opposite directions

the components of a vector are the parts of the vectors that are to each other.

b perpendicular