exam 2 study guide

Forces and Motion

• No force is required to keep a hockey puck sliding at constant velocity on a frictionless surface.
• No force is required to sustain the motion of an object in outer space.

Constant Force and Acceleration

• A constant net force on an object results in constant acceleration.
• If an object's mass is decreasing while a constant force is applied, its acceleration increases.

Forces and Interactions

• When you walk, you push on the floor to the left, and the floor exerts an equal and opposite force on you.
• The force of friction on a sliding object is 10 N, and an applied force of 10 N is needed to maintain a constant velocity.

Gravity and Falling Objects

• A falling object encounters air resistance, which opposes its motion. If the object encounters 4 N of air resistance, the net force on the object is 6 N (10 N - 4 N).
• When a falling object reaches its terminal velocity, its acceleration is 0 m/s².
• Due to air resistance, a ball thrown vertically into the air returns to its starting level with a lower speed than its initial speed.

Newton's Law of Universal Gravitation

• Isaac Newton discovered the law of universal gravitation.
• According to Newton, the greater the masses of interacting objects, the greater the gravitational force between them.
• The difference between Newton's law of universal gravitation as a proportion and as an equation involves the gravitational constant G.

Gravity and Distance

• The force of Earth's gravity on an object in space decreases as the object moves farther away. If the object moves to twice its distance from Earth, the force toward Earth becomes 1/4 of its original value.
• The force of Earth's gravity on an object in space increases as it moves closer. If the object moves to half its distance from Earth, the force toward Earth doubles.

Weight and Gravity

• Your weight is the force of Earth's gravity on you.
• When you weigh yourself on a bathroom scale on an incline, your weight reading on the scale will be lower than on a level surface.

Fundamental Concept

• The concept of force is fundamental to understanding the natural world.

Test your understanding of force and motion with this quiz. Explore questions related to the force required to sustain motion, constant net force, accelerating objects, and friction on sliding objects.