A block weighing 200 N is pushed along a surface. If it takes 80 N to get the block moving and 40 N to keep the block moving at a constant velocity, what are the coefficients of friction μs and μk?  Draw a force diagram.

A 40 N box is resting on a table when a 20 N force is applied to it horizontally. The coefficients of static and kinetic friction are 0.3 and 0.1, respectively. Which of the following best describes the resulting motion of the box?    The motion of the box cannot be determined with the given information.      The box accelerates in the direction of the applied force.      The box remains at rest.      The box moves with a constant velocity in the direction of the applied force.

Mr. Vollmayer pulls his children (21kg and 24kg) on a sled (5kg). The force of the friction on the sled is 60N and he pulls upward at a 25 degree angle relative the the ground. How hard must he pull to move the sled at a constant velocity? what is the normal force acting on the sled?

A 423 N crate rests on a ramp; the maximum angle just before it slips is 26.4° with the horizontal. What is the coefficient of static friction between crate and ramp surfaces?

A 32 kg child puts a 15 kg box into a 12 kg wagon. The child then pulls horizontally on the wagon with a force of 65 N. If the box does not move relative to the wagon, what is the static friction force on the box?

Just like Louis, Maria left a book on the roof of her car before driving away. The mass of the book was 725 grams. The coefficient of static friction between the book and the roof was 0.28. The coefficient of kinetic friction between the book and the roof was 0.23. Maria started her car and drove forward on level ground with an acceleration of 3.6 m/s?. As Maria was driving away with that acceleration, what was the magnitude of the force of friction (in newtons) between the book and the roof of the car?

What is the cofficient of static friction between the pavement and the car tires?

A stationary 10kg object is sitting on the ground. The coefficient of static friction between the object and the ground is 0.8 and the coefficient of kinetic friction is 0.6. How much horizontal force needs to be applied in order to make the object move?

A 55.0 kg block is pulled along a frictionless surface with a force P, exerted at an angle of 25.0 ̊ above the horizontal. What is the minimum force P that will lift the block off the ground? If the block is pulled with half of this force, what will its acceleration be?