Science test 1 (ch. 2 & 3)

Equilibrium

All forces acting on an object are balanced

Force

A push or pull on an object- In English, force is measured in Lbs, but in SI units, force is measured in Newtons

Weight is a force

Is force always required to change to change the state of motion in an object?

YES

Net force

The combination of all forces acting on an object net force on an object changes its motion

Tension

Stretching force

Force vectors

Used to give forces directions

• in math it’s arrows rep force and direction

Vector quantity

Needs both magnitude and direction for a complete description. Force is an example of vector quantity

What can a vector quantity be represented by?

A can graphically be represented by An arrow. The direction of the arrow is the direction of the vector (or force) and the length of the era represents the magnitude (or amount) of the vector

Mechanics

In physics, it is the study of motion or its absent

Mechanical equilibrium

A state wherein no changes in motion occur, an object could be moving or at rest, but it’s motion isn’t changing

Equilibrium rule

Wherever the net force on an object is zero, the object is in mechanical equilibrium

F=force

Net=total

That letter that looks like an E=the sum of

“ The net force is the sum of the forces”

Support force

Upward force that balances weight of an object on a surface Also known as a normal force

Static equilibrium

Objects at rest

Dynamic equilibrium

Objects moving at a constant speed on a straight line

Center of mass ( Center of gravity CG)

The imaginary place that marks the “average” point of miss

Support base

The area bounded by whatever holds the object (objects that can rotate will get their CG as low as possible)

Resultant

The sum of two or more vectors

Inertia

The property of a body to resist changes to its state of motion

Newton’s first law of inertia

Objects in a state of rest tend to remain at rest only forces will change that state

mass

The amount of inertia in an object which depends on the amount of “stuff”present in the object measured in kilograms

Volume

The measure of space and is measure in cubic centimeters cubic meters in liters

Mass ≠ volume

Weight

Force of gravity on an object depends on the mass and measurement in newtons

W=M x G

Is the mass of an object the same in any location?

The mass of an object in any location is the same however, the weight isn’t

What is the relationship between mass and weight?

Miss and we are proportional ( twice the mass weighs twice as much)

g

Gravitational acceleration

what does is g on Earth and Is g the same everywhere?

g= 9.8 N/kg

Density

It’s the object’s mass Divided by its volume-( letter that looks like a p=M/V)

What is the unit of density?

kg/m3

The gymnast shown below is suspended from two non-vertical ropes. The solid vector represents the gymnast weight. What does the dash vector represent?

The resultant of tension in both ropes

What is one of Galileo’s great contributions to physics

Demolishing the notion that a force is necessary to keep an object moving

What is friction and how does it act?

Materials that touch as they move past each other, friction is caused by irregularities and the surfaces that are touching. All irregularities abstract motion, causing a force (friction) that opposes motion

Parallelogram rule

To find a resultant of two factors construct a parallelogram where the two vectors are adjacent sides. The diagonal of the parallelogram shows the resultant