The concrete barrier has a weight of 16,500 N. The coefficient of friction between the barrier and the pavement is μs = 0.40. What is the maximum force P that can be applied to the barrier before it starts moving? Consider all possibilities of motion. (show all possibilities in solution report)

the maximum force P that can be applied to the barrier before it starts moving is 6,600N

Explanation:

Step one :

Applying the equation

P=uR

Where P= force needed to overcome friction

u= coefficient of friction

R=limiting force

Step two :

Given

R=16,500N

u=0.4

Step three :

Substituting our values into the equation we have

P=0.4*16,500

P=6,600N

Hence the maximum force P that can be applied to the barrier before it starts moving is 6,600N

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s