Science 3rd Nine Weeks Test

Question 0

What is distance and displacement and how are the different?

Answer 0

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

Question 1

What is frame of reference?

Answer 1

A system of objects that are not moving with respect to one another

Question 2

What is a vector?

Answer 2

A quantity that has a direction magnitude and direction

Question 3

What happens when combining displacements?

Answer 3

[= -] [-> ->= +]

Question 4

What is a resultant vector?

Answer 4

A sum of two or more vectors

Question 5

What are the three speeds? Define them.

Answer 5

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)

Question 6

What is velocity?

Answer 6

The speed and direction an object is moving, measured relative to a reference point

Question 7

What is force?

Answer 7

A push or pull that acts on an object

Question 8

What is net force?

Answer 8

The overall force acting on an object after all the forces are combined

Question 9

What is a balanced and unbalanced force? What are their differences from each other?

Answer 9

Balanced-the net force is zero and no change in motion

Unbalanced-when acting on an object it causes it to accelerate

Question 10

What are the four frictions?

Answer 10

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

Question 11

What is gravity?

Answer 11

A force between two masses that acts down toward the center of the earth

Question 12

What is terminal velocity?

Answer 12

The constant velocity of a falling object when the force of air resistance equals the force of gravity

Question 13

What is a newton?

Answer 13

The SI unit for force

Question 14

What is projectile motion?

Answer 14

The curved path of an object in free fall after it is given an initial toward velocity

Question 15

Who were the three scientist who studied motion? Describe them.

Answer 15

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

Question 16

Three scientists(continued)

Answer 16

Newton-English scientist who was a student at Trinity college university, and came up with the three laws of motion

Question 17

What is inertia?

Answer 17

Tendency of an object to resist change in motion

Question 18

What are the three motion laws?

Answer 18

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)

Question 19

Motion laws(continued)

Answer 19

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)

Question 20

What is the difference between mass and weight?

Answer 20

Mass-the measure of the inertia of an object

Weight-measure of the force of gravity acting on an object

Question 21

What causes velocity to change?

Answer 21

An unbalanced force

Question 22

Is this true?:acceleration and force act in the same direction when acted on a single object.

Answer 22

Yes it’s true

Question 23

Which would have a bigger gravitational pull the moon or earth?

Answer 23

Earth

Question 24

What is the equation for gravity?

Answer 24

Weight=mass•acceleration due to gravity(w=mg)

Question 25

What causes tides?

Answer 25

The moons gravitational pull

Question 26

What are uses for satellites?

Answer 26

• 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

Question 27

What is momentum measured in?

Answer 27

(Kg•m/s)=mass(kg)•velocity(m/s)

Question 28

How is momentum calculated?

Answer 28

By multiplying mass and velocity

Question 29

What is another equation for the second law of motion?

Answer 29

Acceleration=net force/momentum

A=NF/M

Question 30

Which as a greater momentum, a bowling ball or gold ball?

Answer 30

Bowling ball(greater mass)

Question 31

What two things effect momentum?

Answer 31

Mass and velocity

Question 32

What are the universal forces?

Answer 32

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

Question 33

Forced(continued)

Answer 33

Gravitational-an attractive force that acts between two masses

Question 34

What I are the differences between strong and weak nuclear forces?

Answer 34

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

Question 35

What is Newton’s law of universal gravitation?

Answer 35

Ever in the universe attracts every other object

Question 36

What two things does gravitational force depend on?

Answer 36

Mass and distance

Question 37

What are the only two forces that do both attract and repel?

Answer 37

Electric and magnetic

Question 38

Why does the moon continue is orbit around earth

Answer 38

Because centripetal force keep it moving on its circular path around earth