Chapter 1. Matter in Motion. Section 1: Measuring Motion. A Reference Point is: an object that appears to stay in place Motion: an object’s change in position overtime relative to a reference point Motion can be north, south, east, west, up and down.
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
Matter in Motion
During the interval between the times that these pictures were taken, the hot-air balloon changed position relative to a reference point—the mountain.
Speed: the distance traveled divided by the time interval during which the motion occurred
Speed = distance ÷ time
= 50m ÷ 10s
= 5 m/s
Not everything moves at a constant rate though so you need to be able to calculate average speed.
Average Speed =total distance total time
Step 1: Write the equation for average speed:
Average Speed =total distance total time
Step 2: Replace the total distance and total time with the values given, and solve
If you travel 7.5 km and walk for 1.5 hr, what is your average speed?
An airplane traveling from San Francisco to Chicago travels 1,260 km in 3.5 hr. What is the airplane’s average speed?
The speeds of these cars may be similar, but the velocities of the cars differ because the cars are going in different directions.
A plane passes over point A a velocity of 240 m/s north. Forty seconds later, it passes over point B at a velocity of 260 m/s north. What is the plane’s average acceleration?
Starting velocity = 240 m/s
Final velocity = 260 m/s
Time = 40 s
Plug in your numbers:
260-240 = 20m/s = 0.5m/s2 north
40 s 40s
What is the average acceleration of a subway train that speeds up from 9.6 m/s to 12 m/s in 0.8 s on a straight section of track?
The blades of these windmills are constantly changing direction. Thus, centripetal acceleration is occurring
Force: a push or pull exerted on an object in order to change the motion of the object
Something that you cannot see exerts a force that makes this cat’s fur stand up.
The bulldozer is exerting a force on the pile of soil. But the pile of soil also exerts a force by just sitting on the ground!
When forces act in the same direction, you add the forces to determine the net force. The net force will be in the same direction as the individual forces.
When two forces act in opposite directions, you subtract the smaller force from the larger force to determine the net force. The net force will be in the same direction as the larger force.
Because all the forces on this house of cards are balanced, none of the cards move.
The soccer ball moves because the players exert an unbalanced force on the ball each time they kick it
A boy pulls a wagon with a force of 6 N east as another boy pushes it with a force of 4 N east. What is the net force?
A dog pulls on his chew toy with a force of 10 N towards the east. His owner pulls on the other end f the toy with a force of 15 N to the west. What is the net force?
Friction: a force that opposes motion between two surfaces that are in contact.
When the hills and valleys of one surface stick to the hills and valleys of another surface, friction is created
1) the force pushing the surfaces together and
2) the roughness of the surfaces.
When you work on a bicycle, watch out for the chain! You might get dirty from the grease or oil that keeps the chain moving freely. Without this lubricant, friction between the sections of the chain would quickly wear the chain out.
No one likes cleaning dirty pans. To get this chore done quickly, press down with the scrubber to increase friction.
Gravity:a force of attraction between two objects that is due to their masses
Sir Isaac Newton realized that the same unbalanced force affected the motions of the apple and the moon
Law of Universal Gravitation: All objects in the universe attract each other through gravitational force; the size of the force depends on the masses of the objects and the distance between the objects.
The gravitational force between objects decreases as the distance between the objects increases. The length of the arrows indicates the strength of the gravitational force between two objects
Venus and Earth have approximately the same mass. But because Venus is closer to the sun, the gravitational force between Venus and the sun is greater than the gravitational force between Earth and the sun
Weight:is a measure of the gravitational force on an object; SI unit is Newtons (N)