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Chapter 2
Newton's First Law of Motion-Inertia
Undergraduate 2

Additional Physics Flashcards





Newton's 1st Law



-An object at rest stays at rest.

-An object in motion stays in motion and continues in a straight line at the same speed unless acted upon by a non-0 net force.

-"Law of Inertia"

What is inertia?
The property of things to resist changes in motion.

What is mass?



The bigger the mass, the ____ the inertia.


-the measure of inertia

-how much space an object takes up



What is the difference between mass and weight?
Weight is determind by the gravitational pull of an object, but mass is unchanging no matter the gravitational pull.
What are the two types of motion that Aristotle discussed?
natural and violent
On an inclined plane, as an angle increases, the speed of an object will ________ when going down and ______ when going up.
increase, decrease

Who proved that objects dropped at the same time from the same height will hit the ground at the speed and time?


What causes this?


Name two reasons the falling objects may land at slightly different times.






  • human error
  • air resistance
What is air resistance dependent on? (2)
  • surface area
  • mass distribution of the object
People with (less/more/the same) mass have more terminal velocity.
Name two common experiments that illustrate Newton's 1st Law.
  • the coin in the cup trick
  • the table cloth trick
What is force (in the simplest sense)?
A push or pull.

What is mechanical equilibrium?


Describe what an object at rest does at mechanical equilibrium.


Decribe what a moving object does in mechanical equilibrium.


The state of an object or system of objects for which there are no changes in motion.


If at rest, the state of rest persists.


If  moving, motion continues without change.


What is the equilibrium rule.


Describe it in equation form.


For any object or system of objects in equilibrium, the sum of the forces acting on it equal zero.



Ancient Greek scientists understood some of the properties of ______, but werre confused about _____.
light, motion

Who is considered the "Father of Western Science"?


He was one of the firsts to study ________ seriously.


He attempted to clarify motion by ________.


What was his idea about moving objects?


What were the two main classes he divided motion into? Define each.


Give an example of an object moving to its natural place.


What was his opinion on dropping two objects of varying weights at the same time from the same height?


What type of objects did he think had their own rules about motion and what was his reasoning?


What is the "fifth element" and which objects did he think were made up of this?


Name the only celestial body with a detectable variation from the rest.


Name the normal state of every object excluding celestial bodies, according to this man. Therefore the Earth (moves/doesn't move).


Are pushes and pulls always evident?


What situation did he believe was impossible, so therefore did not put into consideration? What concept did this cause him to overlook?








All motion is due to the nature of the moving object or due to a sustained push or pull. Every object has its proper place in the universe, determined by this nature, and, if not in its proper place, will strive to get there.


natural motion (Proceeds from the nature of the object, dependent on which of the four elements the object contains) and violent motion (imposed forces, resulting from pushing or pulling, that move an object from its proper place)


any of the following would be appropriate

  • clay is made of earth so when you drop it, it hits the ground
  • smoke is made of air, so it floats up
  • feather is made of air and earth, so it will hit the ground, but not as quickly as clay


The heavier of the two would hit the ground 1st, because objects fall at speeds proportionate to their weight.


celestial bodies

earthly objects move up and down and celestial objects move in a circular; up and down has a distinct beginning and in, but circles go on forever


quintessence; celestial bodies


the moon


at rest; doesn't move




vacuums; inertia

What is the formula to find the weight of an object?

In Newton's 1st Law, how does a headrest help guard against whiplash in a rear-end collision?


A monkey hangs stationary at the end of a vertical vine. What two forces act on the monkey? Which is greater?


Can an object be in mechanical equilibrium when only one force acts on it?


Nellie hangs at rest form the end of 2 ropes. How does the reading on the scale compare with her weight?


Your body is not part of the car and therefore wants to stay at rest. When your head jerks back, the headrest stops your head from jerking too far back and therefore prevents whiplash.


Gravity puling the monkey down and the vine pulling the monkey up; neither is greater because he is stationary so the net force is zero.


No, because if only one force acts on it, then the net force will not be zero.


Each scale reads half of her weight.


What is the sum of all the forces in an equation?


What are the two forces acting on a book sitting on a table and what is the sum of the forces?


What letter represents support force?




Net force


Gravity is acting downward. A support force is acting up. net force=zero






What is the equation for equilibrium?


What is the difference between equilibrium and mechanical equilibrium?


When solving for net forces, it is important to notice if ________________.


The length of an arrow in a problem symbolizes _______.


The length of an arrow representing 300 N would be _______ than the arrow representing 50 N.


The friction force equals the ______ or ____ force.


______ and _______ is included in net force.

Sign denotes_____, number denotes _______.




Equilibrium is a general term, and mechanical equilibrium is specifically discussing motion, or lack of motion.


all the forces are represented in the problem






support, applied


direction, magnitude (any order)

direction, magnitude (specific order)

A crate has a 10 N force to the right, a 20 N force to the left, and another 15 N force to the right. Is this equilibrium? If not, what is the net force? What can be done to make it equilibrium?
No, 5 N to the right. If it continues 5 N to the right.

_______ has its own center of mass.


You can balance a pencil on your finger if you put your finger on the _________. The support force of your finger equals ________.




center of mass

the weight of the pencil

Name the three men responsible for overthrowing the Aristotelian view.
Copernicus, Galileo, Newton

Who formulated the theory of moving Earth?


He stated that the simplest way to account for movement of the sun, moon, and planets was to assume _______.


Name the two reasons he didn't make his work public.


What is the name of the journal he wrote on his hypothesis?


What did his hypothesis threaten?




Earth circles the sun


fear of prosecution

doubts about his hypothesis


De Revolutionibis


common church beliefs at that time


Who is responsible for popularizing Copernicus' hypothesis?


What did he discredit and how?


He was the first to provide conclusive _______ and _____.


Because of his findings, he was _______.


He was one of the first to build a _____ and the first to _____. What did he discover by doing this?




Aristotle's views on motion; Leaning Tower of Pisa experiment


observations, experiments


sent to trial and convicted of heresy


telescope; direct it to the night sky; mountains on Jupiter's moons


Who was the first to experiment with inclined planes?


What did he state that contradicted Aristotle's view?


Because of what Galileo saw with the ball and inclined planes, what did he reason about a ball on a flat horizontal surface?


The less friction, the more objects approach ________.






If there is no interference on a moving object, it will keep moving in a straight line forever.


The ball will never speed up or slow down, but will stop because of friction.


constant speed


Two inclined planes facing each other. The ball rolls down first then up the second until __________. Galileo reasoned that this was caused by ______.


When reducing the height of the upward sloping plane the ball (did/didn't) reach the same height and had to go (the same/shorter/farther).


it almost reaches its initial height; friction


did; farther




What causes an object to keep moving straight ahead?


By discovering this, what did Galileo discover about the Earth's motion?


Is inertia the reason a moving object continues in motion when no force acts?




no force is required to keep the Earth moving forward


No, inertia is a property. We do not know the reason.


Who discovered gravity?


What type of math did he invent?


Extended ______ work and formulated 3 laws of _______.


Formulated a theory of the nature of _____ and used _____ to show that ______. This was the experiment that _______.


He invented world's first ________.


He showed that the universe runs according to ______.


He contributed to the _______.


Sir Isaac Newton




Galileo; motion


light; prisms; white light is composed of all colors of the rainbow; made him famous


refelctor telescope


natural laws


Age of Reason

A hockey puck sliding across the ice finally comes to rest. How would Aristotle interpret this behavior? How would Galileo and Newton interpret it?

A: it slides to a stop because it has reached its proper and natural state; rest

G&N: the puck will continue in motion, but will eventually slow down and stop because of the friction acting on it


Calculate the following forces:


Two people pulling on two ends of a rope with the same force.


2 five pound forces in the same direction.


10 pounds exerted to the right and 5 pounds to the left.




10 lbs in that direction


5 lbs to the right


Name the four types of force.


What is a vector quantity?


What is tension?


electrical, magnetic, graviational, muscular effort


A quantity that has both magnitude and direction.


a stretching force


2 lbs is approximately _____ N


Hang a bag of sugar on a string, then on a scale. What forces are acting on the bag?


How do you read "∑F=0"?


A downward force is a (negative/positve/it doesn't matter as long as they're opposite) force. An upward force is a (negative/positive/it doesn't matter as long as they're opposite) force.


Give three other names for an upward force.




tension acting upward, weight acting downward


The vector sum of the forces is zero.


negative; positive


support force, normal force, right angle force


Fred and George are identical twins.


Fred stands alone in the exact middle of a scaffold hanging from scales. The left scale reads 500 N, what does the right one read?


George stands alone, but closer to the right. The left scale reads 170 N. What does the right scale read?


Fred hangs from the right end of the scaffold. The left scale reads zero. What does the right scale read?


500 N


830 N


1000 N


What is the net force on a bathroom scale when a 150 pound person stands on it? Which force equals the weight (the force the scale reads)?


If this person stands on two bathroom scales with their weight evenly divided between the two scales, what will each scale read?


What if they stand with more weight on the left scale?



zero; support force




It will be more than 75 on the left scale and less than 75 on the right scale, but the sum will equal 150.

How can you test if something is in equilibrium?
Note whether or not it undergoes changes in its state of motion (including speed and direction).

The Earth travels at _____ km/s.


Why do we not feel the Earth moving?


Aristotle saw vertical motion as ______ and horizontal motion as _____ because it required a _______.






natural; unnatural; sustained force

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