 # Motion Introduction.

## Presentation on theme: "Motion Introduction."— Presentation transcript:

Motion Introduction

Frozen Time

Frozen Time

Motion Diagram

Motion Diagram

Motion Diagrams

Linear Functions Find the equation of the red trend line in the form y=mx+b, where x is years since 2000 and y is concentration of CO2 in ppm.

What is a “particle”? Any part of an atom
An object that can be represented as a mass at a single point in space A part of a whole An object that can be represented as a single point in time An object that has no top or bottom, no front or back Answer: B

What is a “particle”? Any part of an atom
An object that can be represented as a mass at a single point in space A part of a whole An object that can be represented as a single point in time An object that has no top or bottom, no front or back

What quantities are shown on a complete motion diagram?
The position of the object in each frame of the film, shown as a dot The average velocity vectors (found by connecting each dot in the motion diagram to the next with a vector arrow) The average acceleration vectors (with one acceleration vector linking each two velocity vectors) All of the above Answer: D

What quantities are shown on a complete motion diagram?
The position of the object in each frame of the film, shown as a dot The average velocity vectors (found by connecting each dot in the motion diagram to the next with a vector arrow) The average acceleration vectors (with one acceleration vector linking each two velocity vectors) All of the above

An acceleration vector
tells you how fast an object is going. is constructed from two velocity vectors. is the second derivative of the position. is parallel or opposite to the velocity vector. Acceleration vectors weren’t discussed in this chapter. Answer: B

An acceleration vector
tells you how fast an object is going. is constructed from two velocity vectors. is the second derivative of the position. is parallel or opposite to the velocity vector. Acceleration vectors weren’t discussed in this chapter.

The pictorial representation of a physics problem consists of
a sketch. a coordinate system. symbols. a table of values. all of the above. Answer: E

The pictorial representation of a physics problem consists of
a sketch. a coordinate system. symbols. a table of values. all of the above.

Motion Diagram Concept Questions

Three motion diagrams are shown
Three motion diagrams are shown. Which is a dust particle settling to the floor at constant speed, which is a ball dropped from the roof of a building, and which is a descending rocket slowing to make a soft landing on Mars? A. (a) is ball, (b) is dust, (c) is rocket B. (a) is ball, (b) is rocket, (c) is dust C. (a) is rocket, (b) is dust, (c) is ball D. (a) is rocket, (b) is ball, (c) is dust E. (a) is dust, (b) is ball, (c) is rocket Answer: A

Three motion diagrams are shown
Three motion diagrams are shown. Which is a dust particle settling to the floor at constant speed, which is a ball dropped from the roof of a building, and which is a descending rocket slowing to make a soft landing on Mars? A. (a) is ball, (b) is dust, (c) is rocket B. (a) is ball, (b) is rocket, (c) is dust C. (a) is rocket, (b) is dust, (c) is ball D. (a) is rocket, (b) is ball, (c) is dust E. (a) is dust, (b) is ball, (c) is rocket STT1.2

A particle moves from position 1 to position 2 during the interval ∆t
A particle moves from position 1 to position 2 during the interval ∆t. Which vector shows the particle’s average velocity? Answer: E

A particle moves from position 1 to position 2 during the interval ∆t
A particle moves from position 1 to position 2 during the interval ∆t. Which vector shows the particle’s average velocity? STT1.3

A particle undergoes acceleration while moving from point 1 to point 2
A particle undergoes acceleration while moving from point 1 to point 2. Which of the choices shows the velocity vector as the object moves away from point 2? Answer: C

A particle undergoes acceleration while moving from point 1 to point 2
A particle undergoes acceleration while moving from point 1 to point 2. Which of the choices shows the velocity vector as the object moves away from point 2? STT1.4

Graphical Analysis of Motion Concept Questions

Which position-versus-time graph represents the motion shown in the motion diagram?

Which position-versus-time graph represents the motion shown in the motion diagram?
STT2.1

Which velocity-versus-time graph goes with the position-versus-time graph on the left?

Which velocity-versus-time graph goes with the position-versus-time graph on the left?
STT2.2

The graph of position versus time for a car is given below
The graph of position versus time for a car is given below. What can you say about the velocity of the car over time? a) it speeds up all the time b) it slows down all the time c) it moves at constant velocity d) sometimes it speeds up and sometimes it slows down e) not really sure x t

a) it speeds up all the time
b) it slows down all the time c) it moves at constant velocity d) sometimes it speeds up and sometimes it slows down e) not really sure The graph of position versus time for a car is given below. What can you say about the velocity of the car over time? The car moves at a constant velocity because the x vs. t plot shows a straight line. The slope of a straight line is constant. Remember that the slope of x versus t is the velocity! x t

a) it speeds up all the time
b) it slows down all the time c) it moves at constant velocity d) sometimes it speeds up and sometimes it slows down e) not really sure The graph of position vs. time for a car is given below. What can you say about the velocity of the car over time? t x [CORRECT 5 ANSWER]

The graph of position vs. time for a car is given below
The graph of position vs. time for a car is given below. What can you say about the velocity of the car over time? a) it speeds up all the time b) it slows down all the time c) it moves at constant velocity d) sometimes it speeds up and sometimes it slows down e) not really sure The car slows down all the time because the slope of the x vs. t graph is diminishing as time goes on. Remember that the slope of x vs. t is the velocity! At large t, the value of the position x does not change, indicating that the car must be at rest. x t

Which position-versus-time graph goes with the velocity-versus-time graph at the top? The particle’s position at ti = 0 s is xi = –10 m. Answer: B

Which position-versus-time graph goes with the velocity-versus-time graph at the top? The particle’s position at ti = 0 s is xi = –10 m. STT2.3

A B a) decreases b) increases
c) stays constant d) increases, then decreases e) decreases, then increases Consider the line labeled A in the v versus t plot. How does the speed change with time for line A? v t A B [CORRECT 5 ANSWER]

a) decreases b) increases c) stays constant d) increases, then decreases e) decreases, then increases Consider the line labeled A in the v versus t plot. How does the speed change with time for line A? v t A B In case A, the initial velocity is positive and the magnitude of the velocity continues to increase with time. [CORRECT 5 ANSWER]

A B a) decreases b) increases
c) stays constant d) increases, then decreases e) decreases, then increases Consider the line labeled B in the v versus t plot. How does the speed change with time for line B? A v [CORRECT 5 ANSWER] t B

A B a) decreases b) increases
c) stays constant d) increases, then decreases e) decreases, then increases Consider the line labeled B in the v versus t plot. How does the speed change with time for line B? v t A B In case B, the initial velocity is positive but the magnitude of the velocity decreases toward zero. After this, the magnitude increases again, but becomes negative, indicating that the object has changed direction. [CORRECT 5 ANSWER]

Which velocity-versus-time graph or graphs goes with this acceleration-versus- time graph? The particle is initially moving to the right and eventually to the left. Answer: B

Which velocity-versus-time graph or graphs goes with this acceleration-versus- time graph? The particle is initially moving to the right and eventually to the left. STT2.4

a) both v = 0 and a = 0 b) v ¹ 0, but a = 0 c) v = 0, but a ¹ 0
When throwing a ball straight up, which of the following is true about its velocity v and its acceleration a at the highest point in its path? a) both v = 0 and a = 0 b) v ¹ 0, but a = 0 c) v = 0, but a ¹ 0 d) both v ¹ 0 and a ¹ 0 e) not really sure

a) both v = 0 and a = 0 b) v ¹ 0, but a = 0 c) v = 0, but a ¹ 0
When throwing a ball straight up, which of the following is true about its velocity v and its acceleration a at the highest point in its path? a) both v = 0 and a = 0 b) v ¹ 0, but a = 0 c) v = 0, but a ¹ 0 d) both v ¹ 0 and a ¹ 0 e) not really sure At the top, clearly v = 0 because the ball has momentarily stopped. But the velocity of the ball is changing, so its acceleration is definitely not zero! Otherwise it would remain at rest!! y

The ball rolls up the ramp, then back down
The ball rolls up the ramp, then back down. Which is the correct acceleration graph? Answer: D

The ball rolls up the ramp, then back down
The ball rolls up the ramp, then back down. Which is the correct acceleration graph? STT2.5

Rubber Ball I You drop a rubber ball. Right after it leaves your hand and before it hits the floor, which of the above plots represents the v vs. t graph for this motion? (Assume your y-axis is pointing up). v t a v t c [CORRECT 5 ANSWER] v t b v t d

Rubber Ball I You drop a rubber ball. Right after it leaves your hand and before it hits the floor, which of the above plots represents the v vs. t graph for this motion? (Assume your y-axis is pointing up). v t a v t c [CORRECT 5 ANSWER] v t b v t d

Rubber Ball II You toss a ball straight up in the air and catch it again. Right after it leaves your hand and before you catch it, which of the above plots represents the v vs. t graph for this motion? (Assume your y-axis is pointing up). v t a v t c v t d [CORRECT 5 ANSWER] v t b

Rubber Ball II You toss a ball straight up in the air and catch it again. Right after it leaves your hand and before you catch it, which of the above plots represents the v vs. t graph for this motion? (Assume your y-axis is pointing up). v t a v t c v t d [CORRECT 5 ANSWER] v t b

Rubber Ball III You drop a very bouncy rubber ball. It falls, and then it hits the floor and bounces right back up to you. Which of the following represents the v vs. t graph for this motion? v t a v t b v v t d t b

Rubber Ball III You drop a very bouncy rubber ball. It falls, and then it hits the floor and bounces right back up to you. Which of the following represents the v vs. t graph for this motion? v t a v t b v v t d t b

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