A 105 kg crate initially at rest on a horizontal floor requires a 705 N horizontal force to set it in motion. Once the crate is in motion, it requires a 595 N horizontal force
to keep it moving at a constant velocity. Find the coefficient of static friction and the
coefficient of kinetic friction between the floor and the crate.

μs = 0.68

μk = 0.577

Explanation:

In order to solve this problem, we must remember that the normal force on a body that rests on a horizontal surface is equal to the weight of a body but in the opposite direction.

The friction force is defined as the product of the coefficient of friction by the normal force.

Now when the body is in motion we have that the coefficient of friction is the dynamic one.

595 = μk*N

μk = 595/1030.05

μk = 0.577

Now to start moving it requires a force of 705 [N].

705 = μs*N

μs = 705/1030.05

μs = 0.68

i had this question and the answer was 3.15 miles.

martina travels from school to her mom's office. from there, she walks to school. after school, she walks to the library and then to a friends house before finally ending back at home. find martina's total distance traveled.

a) 0 miles  

b) 0.4 miles  

c) 1 mile  

d) 3.15 miles