# Science Chap. 5

## Terms

undefined, object
copy deck
What is motion?
Motion is when an object changes position over time when compared with a reference point.
What is speed?
The rate at which an objects moves.
What is velocity?
The speed of an object in a particular direction.
What is acceleration?
The rate at which velocity changes.
What is force?
Force is simply a push or pull.
What is a newton?
Newton is a unit in which force is measured by.
What is net force?
Net force is the force that results from combining all the forces exerted on an object.
What is friction?
Friction is a force that opposes motion between two surfaces that are touching.
What is gravity?
Gravity is a force of attraction between objects that is due to their masses.
What is mass?
Mass is the amount of matter in an object, and its value does not change.
To determine if an object is in motion, compare its position over time to a __________ point.
reference
Can a moving object be used as a reference point?
Yes, because if you were on a hot air baloon which is a moving object, you could watch a flying bird overheard, and see it was changing position to your moving balloon.
_______ is the rate at which an object moves.
speed
How fast an object moves depends on the distance traveled and the _______ taken to travel that distance.
time
The SI unit for speed is _____.
m/s (meters/second)
How do you caculate average speed?
total distance/total time
Velocity has speed and ________.
direction
To find the resultant velocity, add velocities that are in ________ directions. Subtract velocities that are in __________ directions.
same;different
How do you calculate acceleration?
final velocity-starting velocity/time it takes to change velocity
Another name for acceleration in which velocity increases is _______ accleration.
positive
Negative acceleration in which velocity decreases is called __________.
deceleration
How can you recognize acceleration on a graph?
Velocity increases as time passes.
True or False?
All forces have size and direction.
True
True or False?
A force is a push or a pull.
True
True or False?
Forces are measured in liters.
False
True or False?
You can exert a push force without there being an object to receive the force.
False
Forces are unbalanced when the net force is not equal to __________.
zero
To start or change the motion of any object, you need an _________ force.
unbalanced
Forces are balanced when the net force applied to an object is __________ zero.
equal to
What force is responsible for the painful difference between sliding on grass and sliding on pavement?
The force that is responsible for this is friction.
True or False?
Friction occurs when the hills and valleys of 2 surfaces stick together.
True
Pavement creates more friction than grass. Why is that?
Pavement is rougher than grass.
True or False?
Friction is affected by the amount of surface that is touching.
False
What kind of friction is this?
A hockey puck crossing an ice rink.
Sliding friction
What kind of friction is this?
Static Friction
What kind of friction is this?
Wheeled cart being pushed
Rolling Friction
What kind of friction is this?
Air rushing past a speeding car
Fluid Friction
Static friction is at work if you try to drag a heavy suitcase along the floor and the suitcase _________.
Doesn't move
As soon as an object starts moving, static friction __________.
disappears
How does friction harm the engine of a car?
It increases temperature and wears down parts.
Why do you need friction to play sports?
If there was no friction, you would not be able to pick up a ball or even run.
What are some ways to reduce friction?
Use a lubricant, make rubbing surfaces smoother, change sliding friction to rolling friction.
The force of attraction between two objects due to their masses is the force of _________---.
gravity
Does all matter experience gravity?
Yes, because matter has mass and gravity is the result of mass.
The force that pulls you toward your pencil is called the __________ force.
gravitational
Since all objects are attracted to each other due to gravity, why can't you see the objects moving toward each other?
The mass of most objects is too small to make an attraction.
How are objects around us affected by the mass of the Earth?
The objects on Earth and the mass of Earth have attraction because of Earth's large mass equals up to a large gravitational gorce.
What did Newton figure out about the moon and a falling apple.
There was an unbalanced force on the apple to make it fall, just liek the moon, except it needs the force to keep it moving in a circle.
Newton's law of universal gravitation describes the rlationships between....
distance, mass, and gravitational force
Which objects are subject to the law of universal gravitation?
Satellites, water, frogs, and stars.
True or False?
If the distance between the objects are the same, the gravitational force between two feathers is greater than the gravitational force between two bowling balls.
False
If two objects are moved _________ each other the gravitational force between them increases.
toward
Why doesn't the sun's gravitational force pull you off the Earth?
The sun is very far away.
What would happen to the Earth and other planets in the solar system without the sun's gravitational gorce?
The planets would not stay in orbit around the sun.
The strength of the gravitational force exerted by an object depends on the ________ of the object. THe measure of the Earth's gravitational force on an object is the object's _______.
mass;weight
Mass or Weight?
Different on the moon
weight
Mass or Weight?
expressed in newtons
weight
Mass or Weight?
measured in grams
mass
Mass or Weight?
measure of gravitational force
weight
Mass or Weight?
Value doesn't change
mass
Mass or Weight?
Amount of matter in an object
mass
True or False?
On Earth, mass and weight are constant which means they are the same thing.
False

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