Chapter 2 Chapter Outline Forces Name:

Per: ___ Date:Lesson 1: Combining Forces

A. What is a force?1. A(n) or is called a force.

2. A(n) is the type of force that is only exerted when two objects are touching.

3. The type of force exerted on one object by another when the objects are not touching is called a(n) .

a. , magnetic force, and are types of noncontact forces.

4. Because forces have magnitude and direction, they are .

a. The unit for the magnitude of a force is the .

B. Combining Forces

1. When one or more forces acts on an object, the forces .

a. The is the combination of all the fordces acting on an object.

2. When the net force on an object is not zero, the forces are said to be .

a. The of an object changes only if unbalanced forces are acting on it.

3. occur when the net force on an object is zero.

a. The of any object does not change if the forces acting on it are balanced.

C. Newton’s First Law of Motion1. The scientist explained how forces cause motion to change.

2. Newton’s first law of motion states that if the net force on an object is

, an object at rest remains at

, or, if the object is moving, it continues to move in a(n)

speed.38.

a. If the net force on an object is zero, the of the object doesn’t change.

3. is the tendency of an object to resist a change in its motion.

a. The more an object has, the more inertia it has.

Lesson 2: Types of Forces

A. What is gravity?

1. Gravity is an attractive force between all object that have .

2. The states that all objects are attracted to each other.

a. According to the law of universal gravitation, the force of attraction between two

objects depends on their and the

between them.

3. The of an object is the gravitational force exerted on it.

a. Weight is a force having magnitude and direction.

b. On Earth, weight is proportional to .

B. Friction

1. The contact force that acts to resist sliding between two touching surfaces is

called .

2. is the force between two surfaces in contact that keep them from sliding when a force is applied.

a. Static means “ .”

3. opposes the motion of two surfaces in contact that are sliding past each other.

C. Elastic Forces1. An elastic force is exerted when a material is

or .

a. The force exerted by a stretched rubber band is an example of

a(n) .Forces 39.

b.The force exerted by a squeezed rubber ball is an example of

a(n) .

2. A table exerts a(n) on a cup resting on its surface.

a. The direction of a normal force is to the surface of the object.

3. By identifying the forces acting on an object, you can predict its .

Lesson 3: Unbalanced Forces and Acceleration

A. Unbalanced Forces and Velocity

1. Whenever an object’s speed or direction changes, a(n) force must be acting on the object.

a.When a resting object is acted on by an unbalanced force, the object will

in the direction of the unbalanced force.

b.An objects speed will when a net force acts in the same direction as the object’s motion.

c. An object’s speed will when a net force acts in the opposite direction of the object’s motion.

d. Unbalanced forces can cause an object to speed up, slow down, or

change .

2.A ball tied to a string and swung in a circle is an example of motion.

a. During circular motion, the acts perpendicular to the velocity, toward the center of the circle.

B. Newton’s Second Law of Motion

1. When an object changes or its velocity change, and the object is accelerating.

Forces 40.

2. states that the acceleration of an object equals the

force divided by the object’s mass.

a.In the equation representing Newton’s second law of motion, force is measure in

and mass is measured in .

b.The units of are meter/second2.

C.Balanced Forces, Unbalanced Forces, and the Second Law.

1.When the is zero, the acceleration is zero.

a.When the acceleration of an object is zero, the is constant.

2.When the net force is not zero, the velocity of the object .

D. Newton’s Third Law of Motion.

1. states that when on object exerts a force on a second object, the second object exerts a(n) force in the opposite direction on the first object.

a. The forces two object exert on each other are called force .

b. The forces in a force pair are in size and

in direction.

c. One of the forces in a force pair is called the and the other force is called the reaction force.

Forces 41.