Newton's First Law of Motion 3.21.12
Newton's First Law of Motion Web Notes
Also called the law of inertia.
http://www.physicsclassroom.com/Class/newtlaws/U2L1a.cfm
1. State Newton's First Law of Motion.
An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
2. What causes motion to change?
When that object was acted upon by an outside force.
3. Ms. Aston decided to buy a hot cop of coffee at her local brewery. Not knowing about Newton/s laws of motion, she placed the cup of coffee in her lap and took off. Much to her surprise the coffee spilled and she crashed into the car in front of her. Using Newton's first law of motion, describe what happened to Ms. Aston's coffee.
The coffee was acted upon by an unbalanced force and it spilled. The container was at rest and she attempted to move it, the container was in motion and you attempted to stop it, or the container was moving in one direction and you attempted to change its direction.
4. Using Newton's first law, describe why we should wear seat belts in our car. Use the animation from the website to help you answer the question.
If we don't wear seat belts, then if we get into a crash we could fly through the windshield. The seat belts will help hold us in place.
A. Click the "Next section Inertia and Mass" button at the bottom of the website.
5. What is inertia?
This tendency to resist changes in their state of motion is described as inertia.
6. What force causes objects to slow and stop? What would happen if that force was not applied? Friction causes object to slow to a stop. If that force was not applied, then the object would keep moving unless acted upon by another force.7. Are the forces required to keep an object in motion? Explain. "Isaac Newton built on Galileo's thoughts about motion. Newton's first law of motion declares that a force is not needed to keep an object in motion. Slide a book across a table and watch it slide to a rest position. The book in motion on the table top does not come to a rest position because of the absence of a force; rather it is the presence of a force - that force being the force of friction - that brings the book to a rest position. In the absence of a force of friction, the book would continue in motion with the same speed and direction - forever! (Or at least to the end of the table top.) A force is not required to keep a moving book in motion."8. Who has more inertia, Mr. Parraz or Mr. Gollner? Explain your answer. Mr. Parraz, because he is heavier, therefore he has more inertia.9. Watch the video at the end of the website and explain how it proves Newton's first law of motion.10. Answer questions 1-7 below the video. Try not to click the answer tab until you have thought about it for yourself. Answer each question in your notebook in complete questions. Make sure and restate the question and the diagram that goes with the question.1. Imagine a place in the cosmos far from all gravitational and frictional influences. Suppose that you visit that place (just suppose) and throw a rock. The rock will
a. gradually stop.b. continue in motion in the same direction at constant speed.
According to Newton's first law, the rock will continue in motion in the same direction at constant speed. 2. A 2-kg object is moving horizontally with a speed of 4 m/s. How much net force is required to keep the object moving at this speed and in this direction?
Answer: 0 N. An object in motion will maintain its state of motion. The presence of an unbalanced force changes the velocity of the object.3. Mac and Tosh are arguing in the cafeteria. Mac says that if he flings the Jell-O with a greater speed it will have a greater inertia. Tosh argues that inertia does not depend upon speed, but rather upon mass. Who do you agree with? Explain why.
Tosh is correct. Inertia is that quantity which depends solely upon mass. The more mass, the more inertia. Momentum is another quantity in Physics which depends on both mass and speed. Momentum will be discussed in a later unit.4. Supposing you were in space in a weightless environment, would it require a force to set an object in motion? Absolutely yes! Even in space objects have mass. And if they have mass, they have inertia. That is, an object in space resists changes in its state of motion. A force must be applied to set a stationary object in motion. Newton's laws rule - everywhere!5. Fred spends most Sunday afternoons at rest on the sofa, watching pro football games and consuming large quantities of food. What effect (if any) does this practice have upon his inertia? Explain.
Fred's inertia will increase! Fred will increase his mass if he makes a habit of this. And if his mass increases, then his inertia increases.6. Ben Tooclose is being chased through the woods by a bull moose that he was attempting to photograph. The enormous mass of the bull moose is extremely intimidating. Yet, if Ben makes a zigzag pattern through the woods, he will be able to use the large mass of the moose to his own advantage. Explain this in terms of inertia and Newton's first law of motion. The large mass of the bull moose means that the bull moose has a large inertia. Thus, Ben can more easily change his own state of motion (make quick changes in direction) while the moose has extreme difficulty changing its state of motion. Physics for better living!7. Two bricks are resting on edge of the lab table. Shirley Sheshort stands on her toes and spots the two bricks. She acquires an intense desire to know which of the two bricks are most massive. Since Shirley is vertically challenged, she is unable to reach high enough and lift the bricks; she can however reach high enough to give the bricks a push. Discuss how the process of pushing the bricks will allow Shirley to determine which of the two bricks is most massive. What difference will Shirley observe and how can this observation lead to the necessary conclusion? The bricks, like any object, possess inertia. That is, the bricks will resist changes in their state of motion. If Shirley gives them a push, then the bricks will offer resistance to this push. The one with the most mass will be the one with the most inertia. This will be the brick which offers the most resistance. This very method of detecting the mass of an object can be used on Earth as well as in locations where gravitational forces are negligible for bricks.11. Click the "Next section state of motion" tab and read through the first couple of paragraphs, then watch the video and answer questions 1-2 in complete sentences. Make sure and restate the question and the diagram that goes with the question.State of MotionInertia is the tendency of an object to resist changes in its state of motion. But what is meant by the phrase state of motion? The state of motion of an object is defined by itsvelocity - the speed with a direction. Thus, inertia could be redefined as follows:
Inertia: tendency of an object to resist changes in its velocity.An object at rest has zero velocity - and (in the absence of an unbalanced force) will remain with a zero velocity. Such an object will not change its state of motion (i.e., velocity) unless acted upon by an unbalanced force. An object in motion with a velocity of 2 m/s, East will (in the absence of an unbalanced force) remain in motion with a velocity of 2 m/s, East. Such an object will not change its state of motion (i.e., velocity) unless acted upon by an unbalanced force. Objects resist changes in their velocity.
As learned in an earlier unit, an object that is not changing its velocity is said to have an acceleration of 0 m/s/s. Thus, we could provide an alternative means of defining inertia:
Inertia: tendency of an object to resist accelerations.1. A group of physics teachers is taking some time off for a little putt-putt golf. The 15th hole at the Hole-In-One Putt-Putt Golf Course has a large metal rim that putters must use to guide their ball towards the hole. Mr. S guides a golf ball around the metal rim When the ball leaves the rim, which path (1, 2, or 3) will the golf ball follow?
The answer is 2. Once leaving the rim, the ball will follow an "inertial path" (i.e., a straight line). At the instant shown in the diagram, the ball is moving to the right; once leaving the rim, there is no more unbalanced forces to change its state of motion. Paths 1 and 3 both show the ball continually changing its direction once leaving the rim.
2. A 4.0-kg object is moving across a friction-free surface with a constant velocity of 2 m/s. Which one of the following horizontal forces is necessary to maintain this state of motion?
a. 0 N
b. 0.5 N
c. 2.0 N
d. 8.0 N
e. depends on the speed.
If an object is in motion, then it will stay in motion with those very same motion characteristics. It doesn't take any force to maintain that same state of motion. In fact, the presence of a force would "ruin" such a state of motion and cause an acceleration.
Also called the law of inertia.
http://www.physicsclassroom.com/Class/newtlaws/U2L1a.cfm
1. State Newton's First Law of Motion.
An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
2. What causes motion to change?
When that object was acted upon by an outside force.
3. Ms. Aston decided to buy a hot cop of coffee at her local brewery. Not knowing about Newton/s laws of motion, she placed the cup of coffee in her lap and took off. Much to her surprise the coffee spilled and she crashed into the car in front of her. Using Newton's first law of motion, describe what happened to Ms. Aston's coffee.
The coffee was acted upon by an unbalanced force and it spilled. The container was at rest and she attempted to move it, the container was in motion and you attempted to stop it, or the container was moving in one direction and you attempted to change its direction.
4. Using Newton's first law, describe why we should wear seat belts in our car. Use the animation from the website to help you answer the question.
If we don't wear seat belts, then if we get into a crash we could fly through the windshield. The seat belts will help hold us in place.
A. Click the "Next section Inertia and Mass" button at the bottom of the website.
5. What is inertia?
This tendency to resist changes in their state of motion is described as inertia.
6. What force causes objects to slow and stop? What would happen if that force was not applied? Friction causes object to slow to a stop. If that force was not applied, then the object would keep moving unless acted upon by another force.7. Are the forces required to keep an object in motion? Explain. "Isaac Newton built on Galileo's thoughts about motion. Newton's first law of motion declares that a force is not needed to keep an object in motion. Slide a book across a table and watch it slide to a rest position. The book in motion on the table top does not come to a rest position because of the absence of a force; rather it is the presence of a force - that force being the force of friction - that brings the book to a rest position. In the absence of a force of friction, the book would continue in motion with the same speed and direction - forever! (Or at least to the end of the table top.) A force is not required to keep a moving book in motion."8. Who has more inertia, Mr. Parraz or Mr. Gollner? Explain your answer. Mr. Parraz, because he is heavier, therefore he has more inertia.9. Watch the video at the end of the website and explain how it proves Newton's first law of motion.10. Answer questions 1-7 below the video. Try not to click the answer tab until you have thought about it for yourself. Answer each question in your notebook in complete questions. Make sure and restate the question and the diagram that goes with the question.1. Imagine a place in the cosmos far from all gravitational and frictional influences. Suppose that you visit that place (just suppose) and throw a rock. The rock will
a. gradually stop.b. continue in motion in the same direction at constant speed.
According to Newton's first law, the rock will continue in motion in the same direction at constant speed. 2. A 2-kg object is moving horizontally with a speed of 4 m/s. How much net force is required to keep the object moving at this speed and in this direction?
Answer: 0 N. An object in motion will maintain its state of motion. The presence of an unbalanced force changes the velocity of the object.3. Mac and Tosh are arguing in the cafeteria. Mac says that if he flings the Jell-O with a greater speed it will have a greater inertia. Tosh argues that inertia does not depend upon speed, but rather upon mass. Who do you agree with? Explain why.
Tosh is correct. Inertia is that quantity which depends solely upon mass. The more mass, the more inertia. Momentum is another quantity in Physics which depends on both mass and speed. Momentum will be discussed in a later unit.4. Supposing you were in space in a weightless environment, would it require a force to set an object in motion? Absolutely yes! Even in space objects have mass. And if they have mass, they have inertia. That is, an object in space resists changes in its state of motion. A force must be applied to set a stationary object in motion. Newton's laws rule - everywhere!5. Fred spends most Sunday afternoons at rest on the sofa, watching pro football games and consuming large quantities of food. What effect (if any) does this practice have upon his inertia? Explain.
Fred's inertia will increase! Fred will increase his mass if he makes a habit of this. And if his mass increases, then his inertia increases.6. Ben Tooclose is being chased through the woods by a bull moose that he was attempting to photograph. The enormous mass of the bull moose is extremely intimidating. Yet, if Ben makes a zigzag pattern through the woods, he will be able to use the large mass of the moose to his own advantage. Explain this in terms of inertia and Newton's first law of motion. The large mass of the bull moose means that the bull moose has a large inertia. Thus, Ben can more easily change his own state of motion (make quick changes in direction) while the moose has extreme difficulty changing its state of motion. Physics for better living!7. Two bricks are resting on edge of the lab table. Shirley Sheshort stands on her toes and spots the two bricks. She acquires an intense desire to know which of the two bricks are most massive. Since Shirley is vertically challenged, she is unable to reach high enough and lift the bricks; she can however reach high enough to give the bricks a push. Discuss how the process of pushing the bricks will allow Shirley to determine which of the two bricks is most massive. What difference will Shirley observe and how can this observation lead to the necessary conclusion? The bricks, like any object, possess inertia. That is, the bricks will resist changes in their state of motion. If Shirley gives them a push, then the bricks will offer resistance to this push. The one with the most mass will be the one with the most inertia. This will be the brick which offers the most resistance. This very method of detecting the mass of an object can be used on Earth as well as in locations where gravitational forces are negligible for bricks.11. Click the "Next section state of motion" tab and read through the first couple of paragraphs, then watch the video and answer questions 1-2 in complete sentences. Make sure and restate the question and the diagram that goes with the question.State of MotionInertia is the tendency of an object to resist changes in its state of motion. But what is meant by the phrase state of motion? The state of motion of an object is defined by itsvelocity - the speed with a direction. Thus, inertia could be redefined as follows:
Inertia: tendency of an object to resist changes in its velocity.An object at rest has zero velocity - and (in the absence of an unbalanced force) will remain with a zero velocity. Such an object will not change its state of motion (i.e., velocity) unless acted upon by an unbalanced force. An object in motion with a velocity of 2 m/s, East will (in the absence of an unbalanced force) remain in motion with a velocity of 2 m/s, East. Such an object will not change its state of motion (i.e., velocity) unless acted upon by an unbalanced force. Objects resist changes in their velocity.
As learned in an earlier unit, an object that is not changing its velocity is said to have an acceleration of 0 m/s/s. Thus, we could provide an alternative means of defining inertia:
Inertia: tendency of an object to resist accelerations.1. A group of physics teachers is taking some time off for a little putt-putt golf. The 15th hole at the Hole-In-One Putt-Putt Golf Course has a large metal rim that putters must use to guide their ball towards the hole. Mr. S guides a golf ball around the metal rim When the ball leaves the rim, which path (1, 2, or 3) will the golf ball follow?
The answer is 2. Once leaving the rim, the ball will follow an "inertial path" (i.e., a straight line). At the instant shown in the diagram, the ball is moving to the right; once leaving the rim, there is no more unbalanced forces to change its state of motion. Paths 1 and 3 both show the ball continually changing its direction once leaving the rim.
2. A 4.0-kg object is moving across a friction-free surface with a constant velocity of 2 m/s. Which one of the following horizontal forces is necessary to maintain this state of motion?
a. 0 N
b. 0.5 N
c. 2.0 N
d. 8.0 N
e. depends on the speed.
If an object is in motion, then it will stay in motion with those very same motion characteristics. It doesn't take any force to maintain that same state of motion. In fact, the presence of a force would "ruin" such a state of motion and cause an acceleration.