1. PH Force Assignment 1a. Net force is the combination of all forces acting on an object. The net force determines whether an object moves and also in which direction it moves. 1b. 2a. To calculate the net force, you combine the opposing forces by subtraction. 2b. Balanced forces cancel and do not change the object’s motion. Unbalanced forces cause the object’s motion to change. 2c. The net force is 270N

2. 2a. Static Friction- The friction that acts on objects that are not moving. Sliding friction- occurs when two solid surfaces slide over each other. How might you increase or decrease sliding friction?

3. Rolling Friction- when an object rolls across a surface. Fluid friction- occurs when a solid object moves through a fluid.

4. 3a. Buoyant force- acts in the direction opposite to the force of gravity, so it makes an object feel lighter. The less dense an object is, the greater the buoyant force it experiences. Archimedes’ principle- states that the buoyant force acting on a submerged object is equal to the weight of the volume of fluid displaced by the object.

5. 3b. 1a. Density equals mass per unit volume. 1b. If the object’s density is greater than that of water, the object will sink; if the object’s density is less than that of water, the object will float. 1c. Because water cannot enter these compartments, the air inside them gives the canoe a greater volume while adding only slightly to the canoe’s mass. This makes the canoe less dense than water even if the material the canoe is made of is denser than water.

6. 3b. 2a. The buoyant force acts upward on a submerged object, making the object seem lighter. 2b. The buoyant force on the object equals the weight of the fluid displaced by the object. 2c. Because the object floats, the weight of the displaced water equals the weight of the object, 340 N. The buoyant force on the object equals its weight, 340 N.

7. 4. 23. The object weighs less in water because the buoyant force on it in water is opposite to the force of gravity. 24. The buoyant force is 2.0 N. 25. The volume of water above the dotted line is equal to the volume of the object. The weight of the volume of displaced water is equal to the buoyant force on the object, 2.0 N.