Friction Problems                                                Name __________________

(Assume the object is sliding for #1-10) – SHOW ALL WORK and USE PICTURES

1. A force of 40.0 N is applied to move a 12.0 kg object with a constant velocity.  What is the coefficient of friction?

2. What force is necessary to move a 10.0 kg object with a constant velocity if the coefficient of friction is 0.280?

3. A force of 65.0 N is used to move an object with a constant velocity where the coefficient of friction is 0.300.  What is the mass of the object?

4. What force is necessary to accelerate a 15.0 kg object at 4.00 m/s2 when the coefficient of friction is 0.250?

5. A force of 34.3 N is applied to 10.0 kg object where the coefficient of friction is 0.350.  What is the acceleration?

6. A force of 25.0 N is applied to 10.0 kg object where the coefficient of friction is 0.350.  What is the acceleration?

7. A force of 50.0 N is applied to 10.0 kg object where the coefficient of friction is 0.350.  What is the acceleration?

8. A 100.0 N force is necessary to accelerate a 15.0 kg object at 4.70 m/s2.  What is the coefficient of friction?

9. A 120.0 N force is applied to a 20.0 kg object where the coefficient of friction is 0.200.  What is the acceleration?

10. A 120.0 N force is applied to a 20.0 kg object where the coefficient of friction is 0.380.  What is the acceleration?

11. A 50.0 kg diver falls from a 20.0 m platform.  A) With what force does she hit the surface of the water?  B) With what velocity does she hit the surface of the water?  C) If she stops 3.00 m below the surface of the water, what is her acceleration under the water?  D) What force does the water exert on her to bring her to a stop?

12. A 25.0 kg object falls toward the surface of the Earth (m = 5.979 x 1024).  A) What force does the Earth exert on the object?  B) What force does the object exert on the Earth?  C) What is the rate of acceleration of the Earth toward the object?

Answers:        1) 0.340        2) 27.4 N        3) 22.1 kg        4) 96.8 N        5) 0 m/s2                        6) 0 m/s2        7) 1.57 m/s2        8) 0.201        9) 4.04 m/s2        10) 2.28 m/s2        11) –4.90 x 102 N; -19.8 m/s; 65.3 m/s2; 3270 N      12) –245 N; 245 N; 4.10 x 10-23 m/s2