Science 3rd Nine Weeks Test Flashcards
What is distance and displacement and how are the different?
Distance-it’s the length of a PATH between TWO points
Displacement-it’s the DIRECTION of a starting point and the length of a straight line from start to finish
What is frame of reference?
A system of objects that are not moving with respect to one another
What is a vector?
A quantity that has a direction magnitude and direction
What happens when combining displacements?
[= -] [-> ->= +]
What is a resultant vector?
A sum of two or more vectors
What are the three speeds? Define them.
Speed-the ratio of the distance an object moves to the amount of time it moves. The SI unit of it is m/s
Instantaneous speed-measured at a particular instant
Average speed-computed to the entire duration of the trip(v=d/t)
What is velocity?
The speed and direction an object is moving, measured relative to a reference point
What is force?
A push or pull that acts on an object
What is net force?
The overall force acting on an object after all the forces are combined
What is a balanced and unbalanced force? What are their differences from each other?
Balanced-the net force is zero and no change in motion
Unbalanced-when acting on an object it causes it to accelerate
What are the four frictions?
Static-friction that acts on objects that don’t move(strongest)
Sliding-opposes to direction of motion of an object as it slides
Rolling friction-acts on rolling objects(weakest)
Fluid friction-opposes motion of an object through fluid
What is gravity?
A force between two masses that acts down toward the center of the earth
What is terminal velocity?
The constant velocity of a falling object when the force of air resistance equals the force of gravity
What is a newton?
The SI unit for force
What is projectile motion?
The curved path of an object in free fall after it is given an initial toward velocity
Who were the three scientist who studied motion? Describe them.
Aristotle-ancient Greek philosopher who made discoveries through careful observations and logic. He was not always correct
Galileo-Italian scientist who studied to find out about the world. Made the telescope
Three scientists(continued)
Newton-English scientist who was a student at Trinity college university, and came up with the three laws of motion
What is inertia?
Tendency of an object to resist change in motion
What are the three motion laws?
1st law(law of inertia)-an object at rest tends to stay at rest and an object in motion tends to stay in motion unless acted on by an outside unbalanced force(kicking a soccer ball to make it move)
Motion laws(continued)
2nd law(acceleration)-the acceleration of an object is equal to the net force acting on it dived by its mass. Doubling the mass cuts the acceleration in half(a=f/m)(truck v. Car down a hill) 3rd law-whenever an object releases force on another that object had an equal opposite reaction to the force(when you walk on the ground)
What is the difference between mass and weight?
Mass-the measure of the inertia of an object
Weight-measure of the force of gravity acting on an object
What causes velocity to change?
An unbalanced force
Is this true?:acceleration and force act in the same direction when acted on a single object.
Yes it’s true
Which would have a bigger gravitational pull the moon or earth?
Earth
What is the equation for gravity?
Weight=mass•acceleration due to gravity(w=mg)
What causes tides?
The moons gravitational pull
What are uses for satellites?
- uses telescopes to gaze into space
- monitors earth’s weather
- receives and transmits cell phone and satellite TV signals
- creates detailed maps of earth’s surface
What is momentum measured in?
(Kg•m/s)=mass(kg)•velocity(m/s)
How is momentum calculated?
By multiplying mass and velocity
What is another equation for the second law of motion?
Acceleration=net force/momentum
A=NF/M
Which as a greater momentum, a bowling ball or gold ball?
Bowling ball(greater mass)
What two things effect momentum?
Mass and velocity
What are the universal forces?
Strong nuclear-powerful,attractive force that combines the neutrons an protons together in the nucleus
Weak nuclear-powerful,attractive force that acts over a short distance
Electromagnetic-force associated with charged particles that had two aspects:electric and magnetic force
Forced(continued)
Gravitational-an attractive force that acts between two masses
What I are the differences between strong and weak nuclear forces?
Strong-acts on protons and neutrons,VERY short range,and very strong(100 times stronger than the electrical force)
Weak-acts on all particles,short range,weaker than the strong force
What is Newton’s law of universal gravitation?
Ever in the universe attracts every other object
What two things does gravitational force depend on?
Mass and distance
What are the only two forces that do both attract and repel?
Electric and magnetic
Why does the moon continue is orbit around earth
Because centripetal force keep it moving on its circular path around earth
