Unit 1 Forces and Motion

Flashcards covering forces, motion, Newton's Laws, mass versus weight, gravitational pull, terminal velocity, and formulas from the Unit 1 Study Guide.

What are forces, and under what condition do they cause an object to change its motion?

Forces are any pushes or pulls. They cause an object to change its motion if the forces are not balanced and the net force is greater than $0$.

What two factors must an applied force overcome to slide an object across the floor?

An applied force must overcome the weight of the object and the friction of the object with the floor.

How does friction affect the motion of an object?

Friction always opposes motion.

According to Newton's 1st Law, how does an object behave when the forces acting on it are balanced?

The object will move at a constant velocity, meaning if it is at rest, it will remain at rest, and if it is moving, it will not speed up, slow down, or change direction.

What is another name for Newton's 1st Law?

Newton's 1st Law is also known as the Law of Inertia.

What is inertia, and how is it related to an object's mass?

Inertia is the resistance to a change in motion. Objects with more mass have more inertia.

What two factors determine the gravitational pull between two objects?

The gravitational pull depends on the mass of the objects and the distance between the objects. Bigger mass increases gravitational pull, while greater distance weakens it.

What property must an object possess to exert a gravitational pull?

Anything that has mass exerts a gravitational pull.

What is mass, in what unit is it measured, and does it depend on gravity?

Mass is the amount of matter that makes up an object, measured in $\text{kg}$. Mass does NOT depend on gravity.

What does weight depend on, and in what unit is it measured?

Weight depends on the pull of gravity and is measured in Newtons.

How do you calculate weight from mass, and how do you convert mass given in pounds to kilograms?

To calculate weight, multiply mass in kilograms by the acceleration due to Earth's gravity ($9.8\text{ m/s/s}$). If mass is given in pounds, divide by $2.2$ to convert it to kilograms.

When does terminal velocity occur, and how does an object move when it reaches terminal velocity?

Terminal velocity occurs when the upward force of air resistance is equal to the downward pull of gravity. At this moment, the object will continue to fall at a constant rate.

What is the formula to calculate acceleration using initial velocity, final velocity, and time?

$$a = \frac{V_f - V_i}{t}$$

What is the formula to calculate force using mass and acceleration?

$$F = ma$$

What is the formula to calculate acceleration using force and mass?

$$a = \frac{F}{m}$$

What does Newton's 3rd Law state, and why does a bowling pin accelerate away from a bowling ball when they collide with $50\text{ N}$ of force?

Newton's 3rd Law states that all forces act in pairs that are equal and opposite. When a bowling ball collides with a pin with $50\text{ N}$ of force, the pin pushes back with $50\text{ N}$ of force, but the pin accelerates away because it has less mass.

What relationship regarding mass and force is explained by Newton's 2nd Law?

Newton's 2nd Law explains how objects with more mass require more force to accelerate.

What is the equation to calculate average speed?

$$S = \frac{d}{t}$$