Study-Guide for Test Newton's Laws - Forces in Two Dimensions 1. An 80-N applied force accelerates a 20-kg box across a horizontal sheet of frictional surface. It is pulled at the angle of 30. The coefficient of kinetic friction between the box and a horizontal sheet is 0.270. What is the acceleration of the box? 2. A box is pushed at a constant speed of 0.30 m/s across a frictional surface. It is pushed with the force of 140.0 N at the angle of 40 to the ground. The box is weighting 240 N. What is the coefficient of the kinetic friction? 3. Find the Normal Force. A toddler is in elevator. The mass of a toddler is 20 kg. a. Elevator accelerates 2.0 m/s up b. Elevator is at rest c. Elevator accelerates 2.5 m/s down d. Elevator is in free fall a. 35" with the horizontal b. 58 with the surface c. 38 with the horizontal d. 30 with surface Fapp. 35 N Fapp, 80 N Fapp, 45 N F app. 55 N 4. A student attaches a rope to a 30.0 kg box of books. He pulls the box at a constant speed with a force of 70.0 N at an angle of 25 with the horizontal. Find the coefficient of kinetic friction between the box and the floor. 5. A box of books is pushed with the force of 450 N at an angle of 35 downward below the horizontal. The mass of the box is 40-kg. The coefficient of kinetic friction is 0.344. What is the acceleration of the box? 6. A bag of sugar has a mass of 3.50 kg. What is its weight in newtons a. on the moon (acceleration due to gravity is one-sixth on Earth) b. on Jupiter (acceleration due to gravity is 2.64 times that on Earth)_ 7. A 65-kg person on skis is going down a hill sloped at 35. The coefficient of kinetic friction between the skis and the snow is 0.120. What is the acceleration? 8. A sled slides from rest at the top of snow covered hill. If the hill a 28 and the coefficient of kinetic friction between the sled's runners and the snow hill is 0.130, what is the acceleration? 9. A 65 kg box slides down a 40 ramp with an acceleration of 3.50 m/s. Find kinetic between the box and the ramp. 10. A 2.5 kg mass starts from rest and slides down an 50 icy inclined plane 0.8 m long in 0.50 s. What is the coefficient of the kinetic friction between the mass and the plane? (Ax = vit + at) 11. A 60-kg person on skis is going down a hill sloped at 35. The coefficient of kinetic friction is 0.140. How fast is the skier going 5.0 s after starting from rest? (v = v+ast) Bonus A 30.0-kg suitcase slides down an angle ramp with acceleration of 2.8 m/s. The Normal Force is 249 N. Find the coefficient of kinetic friction between the suitcase and the ramp.