1.Phoebe Physics pulls a wagon with a force of 80 N. a) What is the net force if the force of friction between the wagon and the ground is 12 N? b) If she uses 80 N to pull the wagon through a mud puddle, and the net force on the wagon is 38 N, what friction force acts on the wagon?

2.A rocket weighs 2.0 x 107 N. Its engines exert 2.5 x 107 N of force at lift-off. What is the net force applied to the rocket?

3.Two children having a disagreement pull on a sled in opposite directions. One pulls with a force of 200 N east, the other with a force of 175 N west. A friction force of 10 N exists between the sled and the surface. Determine the net force on the sled.

4. A heavy wagon is pulled along the sidewalk by a force of 12 N, with a 10 N force opposing the motion. The force of gravity on the wagon is 20 N. a) Draw a f.b. diagram showing all the forces acting on the wagon. b) Determine the net force on the wagon.

5.A 400 N force pulls due north on a crate. What other force must act on the crate if: a) the net force on the crate is 386 N due south? b) the net force on the crate is 152 N due north?

6.A 2.5 kg block has a force of sliding friction between it and a level surface of 3.5 N. This block is pulled by an applied force of 14 N. a) Find the coefficient of sliding friction between block and surface. b) What is the unbalanced force as the block is moved? c) What is the acceleration of the block?

7.A 15 kg mass is accelerated at 2.0 m/s2 along a horizontal table. a) What net force is acting on this mass? b) A friction force of 7.0 N acts on the mass above. What is the coefficient of sliding friction between mass and table? c) Given the friction force in b), what applied force is needed to accelerate this mass at 2.0 m/s2 ?

8.What is the coefficient of sliding friction if a force of 400 N is required to pull a 55 kg crate on a horizontal warehouse floor at constant speed?