SEM - Lesson 1 - Motion
What is acceleration?
Acceleration measures how much the velocity of an object progressively changes.
How do you know an object is moving?
An object is moving if its position relative to a fixed point is changing.
In terms of motion which direction is positive and negative?
Any direction can be positive or negative because it is relative to the person doing calculations, but the negative direction has to stay negative throughout the entire calculation and the positive direction has to stay the positive direction.
How do you calculate average speed?
Average speed is calculated by dividing total distance covered by time.
How are forces connected with motion?
Changes in motion cannot occur without some kind of force acting on the object.
Can displacement be negative?
Displacement can be negative to indicate a direction. For example one could say 5km south or -5km.
Can distance be negative?
Distance cannot be negative because as long as the object is moving at all, in any direction, the distance is increasing. If an object is not moving, the distance is zero.
Why is physics sometimes challenging for us to understand?
Physics can be challenging for us to understand because everyone has their own perception of what physics, but the average person's understanding of physics is normally wrong.
What is the difference between distance and displacement?
The distance is the amount the object has moved while the displacement only accounts for the object's final position. Displacement includes a numeric value and the direction the object is in in its final position in comparison to its original.
What is distance?
The distance travelled is the entire length of the path, so how far an object travelled to get to its final position
Describe a position v. time graph for: staying in the same spot for 3 seconds?
The graph would be a straight line because as 3 seconds go by the position has not changed
Describe a position v. time graph for: coasting at 1 meter per second?
The graph would have a constant slope because the position and time are changing together at a constant rate
Describe a position v. time graph for: after 1 second you have gone 1 meter, after 2 seconds you have gone 4 meters, and after 3 seconds you have gone 9 meters?
The graph would not be a constant line because I would be accelerating. It would look like a steeper line because I would be moving faster each second.
What is acceleration?
a change in velocity
What is motion?
a description of your place in the universe using conditions like positions, velocity, and acceleration
Explain: "Even things that appear to be at rest move."
This statement is valid because movement is relative to other objects. For example, when sitting in a car someone can be at rest relative to his/her seat, but in reality the car is moving at 60 mph so the person is also moving at this speed.
How do you calculate the speed of an object?
by dividing the distance the object moved by the time it took
In terms of motion, what is time?
how long something has been happening
What are the main units that are used when we are describing speed?
miles per hour, kilometers per hour, centimeters per day, and light-years per century
What is velocity?
Velocity is a vector quantity of how fast something is going.
Why can't you feel the Earth's motion?
We can't feel Earth's motion because it is moving mainly in at a constant speed and in a constant direction.
What does the author mean when he says you are really moving (at very high speeds) even when you are sitting still at your computer?
When the author says that we are really moving even when sitting still he means that the Earth is rotating and revolving extremely fast beneath us, so in turn we are also moving.
What is average speed?
the average rate of speed throughout the entire distance covered
In terms of motion, what is displacement?
the change in position
What is displacement?
the difference between the object's original position and the position it ends in
What is physics?
the science of how the world works and moves
What is instantaneous speed?
the speed at any given instant.
In terms of motion, what is velocity?
the way an object's position changes over time
What are forces?
Forces are invisible pushes and pulls that act upon objects to start or change their movements.
Who determined that you could measure speed as more than "slow" or "fast?"
Galileo
What did you guess in the golf ball and fan situation? Were you right or wrong?
I guessed that the golf ball would curve in towards the fan because of the spinning motion. I was wrong because the golf ball would just travel in a straight line.
Explain the author's statement in your own words: "To truly learn physics is to approach the universe once again as a child - but this time, armed with the power of science."
If we want to genuinely understand physics we have to get rid of our own perceptions that we have developed over the years and go back to the clean slate we had as children, along with our real knowledge of science.
What kind of speed does a car's speedometer tell us?
Instantaneous speed
What is mass?
Mass is a measurement of quantity, usually in grams or kilograms.
What is mechanics?
Mechanics is the study of motion through forces, acceleration, mass, velocity, energy, and work.
What is one-dimensional motion?
Motion in which the object can only move back and forth on a straight line
What is the difference between simple and complex movement?
Simple movement involves straight lines and direct paths while complex movement is when the object's direction has/will change. Complex movement requires some kind of force acting upon the object.
What is speed?
Speed is how fast an object is moving.
In terms of motion, what is position?
where something was or is
