AP Physics 1 - Unit 2

If the net force acting on the object is zero, then the net force is...

zero

Force

Any push or pull acting on an object

Is force a scalar of vector?

Vector

SI units for force

Newtons (N)

How to calculate net force

Add vector values along a single axis

The direction of the net force is ... as the direction of the acceleration.

the same

Free body diagram

A way to visualize all of the external forces acting on an object

Two ways an object can have zero acceleration

- Remains stationary

- Moves at constant velocity

If an object's direction of motion and acceleration point in the SAME direction, its speed ...

Increases

If an object's direction of motion and acceleration point in DIFFERENT directions, its speed ...

Decreases

Newton's 2nd law of motion

F=ma

In Newton's 2nd Law equation, what units must you use for mass?

Kilograms (kg)

In Newton's 2nd Law equation, what units must you use for acceleration?

m/s^2

How are net force and acceleration related?

Directly proportional

How are mass and acceleration related?

Inversely proportional

Whenever two objects are in contact, what forces do they exert on each other?

Equal and opposite

When standing on a scale, what is the scale actually measuring?

Normal force

The point in an elevator ride that you feel heavier than normal

When Fn > Fg, which occurs when acceleration is upwards

The point in an elevator ride that you feel lighter than normal

When Fn < Fg, which occurs when acceleration is downwards

Gravitational acceleration (g)

9.8 m/s^2 down

Gravitational force

m x g (N)

Mass

An inherent property of an object (kg)

Weight

Magnitude of gravitational force (N)

How are mass and weight different?

Mass never changes; weight varies based on g

Normal force

Force of surface pushing "up" on object

If you pull upwards, with a force greater than an object's gravitational force (weight), what happens to the normal force?

Normal force goes to zero, and the object lifts in the air.

Tension force

Force from a rope on an object when rope is pulled taut

Direction of tension force

Along rope, away from object

If two objects are connected by a string, how does the magnitude of the tension force on each object compare?

The forces on each object are the same

Static friction

Resistive force that is preventing an object from sliding along surface

Kinetic friction

Resistive force when 2 surfaces are sliding against each other

What direction does friction force act on an object?

Opposite direction of motion

EQUATION for kinetic friction

fk = µk x Fn

EQUATION for static friction

fs ≤ µk x Fn

Coefficient of friction

Measure of surface roughness, depends on both materials

The coefficient of static friction (µs) is ... the coefficient of kinetic friction (µk)

greater than