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8th Grade Study Guides > Science Test Topic 3 > Flashcards

Science Test Topic 3 Flashcards

1
Q

A place or object used for comparison to determine whether something is in motion.

A

Reference Point

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2
Q

What Does Relative Motion State?

A

The referance point is a point for the moment. Because its not relatively moving. For example if you are driving alongside a car and it looks as if its not moving.

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3
Q

A push or pull

A

A force

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4
Q

The unit for the strength of a force is called..

A

Newton

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5
Q

A contact force that two surfaces exert on each other when they rub against each other.

A

Friction

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6
Q

A force that pulls objects towards each other as a result of their masses.

A

Gravity

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7
Q

If two forces acting on an object are equal in strength and opposite in direction.

A

The forces are balanced and the it has an equal net-force.

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8
Q

When the forces of an object are unbalanced, there is a nonzero net force acting on the object.

A

True

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9
Q

What sources of information might you use to determine the relative motion of Earth compared to other planets in the solar system?

A

I might go online and find the speed and locations of the planets relative to earth.

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10
Q

I might go online and find the speed and locations of the planets relative to earth.

A

Gravity acts in the opposite direction

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11
Q

The distance an object moves per unit of time

A

Speed

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12
Q

The amount of something that occurs or changes in one unit of time…

A

Rate

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13
Q

The speed at a particular instant in time is called.

A

instantaneous speed

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14
Q

Suppose you drove a distance of 8 kilometers in 2 hours while in heavy traffic. Then, it took you 3 hours to drive 160 kilometers from one side of a city to the other. Finally, you traveled 482 kilometers on an interstate highway for 10 hours.

What is the total distance traveled?
What is the total time it took to travel?
What was the average speed?

A
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15
Q

The speed at which an object travels in a given direction…

A

Velocity

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16
Q

Calculate it : Initial Speed = 2 m/s
Final Speed = 68 m/s
Time = 4 seconds

What is the acceleration?

A
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17
Q

An object that is traveling at a constant speed is accelerating when it changes direction

A

True

18
Q

How can understanding velocity help to prevent a mid-air collision between airplanes?

A

you can determine the velocity of the planes and if they are going towards each other and how fast to prevent a collision.

19
Q

How does instantaneous speed differ from average speed?

A

instantaneous speed is speed that happens in an instance, while average speed is speed that is the average over time, instead of instantly speeding up.

20
Q

Any change in speed or any change in direction.

A

Acceleration

21
Q

Briefly describe Newton’s First Law of Motion

A

An object that is at rest will stay at rest unless acted upon. An object that is in motion will stay in motion unless acted upon.

22
Q

Resistance to change in motion is called

A

Inertia

23
Q

The more mass an object has the _________ the inertia

A

greater

24
Q

How does changing the mass of an object affect its acceleration?

A

The more mass the more acceleration is needed to accelerate the object because of its weight.

25
Q

Newton’s Second Law of Motion created which of these formulas?

A

Net Force = Mass x Acceleration

26
Q

Briefly describe Newton’s Third Law of Motion.

A

for every action their is an equal but opposite reaction. For example, if two cars hit each other they would both bounce (jerk backwards, move backwards) back because of Newtons third law, they both bounce back because they have equal but opposite reactions.

27
Q

In order for forces to balance, they must act on the same object

A

true

28
Q

When a hockey player hits a puck with his stick, the action force is the force of the stick on the puck.

A

true

29
Q

Another way to state Newton’s __________ law is that for every action there is an equal, but opposite, reaction.

A

third

30
Q

(3 PART ANSWER)

A basketball is shot and experiences a net force of 5N, which causes it to accelerate at 10 m/s. What is the mass of the volleyball?

The same ball is hit again and experiences a net force of 8N instead. What is the acceleration of the volleyball?

The same ball rolls horizontally along the court and decelerates at a rate of 3m/s. Calculate the force of friction that cause this deceleration.

A

M= 0.5 A=16 F= 1.5

31
Q

In general, smoother surfaces produce less friction than rough surfaces.

A

true

32
Q

The less mass an object has, the greater the gravitational force between it and other objects.

A

false

33
Q

If you know the mass of an object in kilograms, you can calculate its weight on Earth using Newton’s __________ law.

A

second

34
Q

The type of potential energy that we associate with gravity is called…

A

GPE (Gravitational Potential Energy)

35
Q

When a skydiver jumps from a helicopter, a net force acts on his body as he falls. This net force is a combination of which two things?

A

gravity and friction

36
Q

Give one example of gravity that you might see everyday

A

When you throw a ball up in the air and it comes back down.

37
Q

Give one example of a non-contact force.

A

Magnetism

38
Q

If friction didn’t exist, when would a moving object stop moving

A

If friction didn’t exist, then an object would keep going forever

39
Q

Write an argument supported by evidence that explains why the pencil and the notebook resting on your desk are not being pulled together by the force of gravity between them.

A

The masses of an the objects are too small, so the gravity’s force cannot overcome other forces. The more mass an object has, the greater the gravitational force between it and other objects. SO the less mass an object has the less gravitational force is between it and other objects.

40
Q

What is the law of universal gravitation?

A

The force of gravity acts on all objects in the universe that have mass. So any two objects that have mass, attract to each other

8th Grade Study Guides (13 decks)

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