What is the difference between speed and velocity?
Speed- how fast something is going
Velocity- how fast something is going AND its direction
What is the acceleration of a car that increases its velocity from 0 too 100 km per hour in 5 seconds
20 km per hour/per second
Galileo performed the following experiments with balls rolling down ramps? Why?
1) Falling Vertically happens too fast
2) He wanted to show that acceleration is constant for each ramp.
3) He wanted to show how the distance fallen depends on the time^2
Which is greater, an acceleration from 25 km/h to 30 km/h or one from 96 km/h to 100km/h if both occur during the same same time interval. Explain.
25-30 is a greater acceleration.
Can automobile with a velocity toward the north simultaneously have an acceleration towards the south. Explain and give real examples.
Yes if it is slowing down. EX. a car.
Starting from rest, one car accelerates to a speed of 50 km/h, and another car accelerates to a speed of 60 km/h. Which car underwent the greater acceleration? Explain
Neither, we don't know the time.
What is the relationship between frequency, wavelength, and wave speed.
Wave speed= wave length x frequency
A sound has a wave length of 2 meters, what is the frequency of the sound?
330= 2 x frequency
divide by 2
Why doesn't the frequency of a simple pendulum depend on its mass?
1. Mass creates weight, but mass resists change.
You clamp one end of a hacksaw blade in a vice and twang the free end. It vibrates. Now repeat, but first put a wade of clay on the free end.
a. Does the hack saw blade act like a pendulum?
No because the restoring force is not gravity
b. In class I said that the vibrating hack saw blade can be better understood if i thought of as something else. I talked about a sport. What is the sport and how does the sport help us understand the hacksaw blade?
Ice Skating is the sport. Rotational Inertia. (draw picture)
Does the medium in which a wave travels move with the wave? Give an example to support your answer.
No, it is just going up and down. Think of a stick in a pond, not left and right just up and down.
If the speed of sound depends on its frequency, would you enjoy a concert?
No, high pitches get to your ear sooner than low pitches.
The sine curve at right shows a flute played into a microphone. The graph was created using the software and microphone that I used in class. Draw on the graph below.
Higher pitch- more frequency(make more)
Louder sound- higher amplitude(make them longer)
When a person throws a ball straight up, in the absence of air resistance, by how much does the speed of the ball increase each second while coming back down? Which takes longer, the time for the ball to go up or the times for the ball to come back down?
a. 10 m/s every second
b. same amount
Why does a stream of water get narrower as it falls from a faucet? Explain. See picture at right.
Gravity. Water is moving faster that has been falling longer.
If you drop an object, its acceleration toward the ground is 10 m/s^2. If you throw it downward instead, would its acceleration be greater than 10 m/s^2? Explain.
No, acceleration due to gravity is ALWAYS 10 m/s^2. Gravity doesn't care about speed.
Referring to the ball/hill figures at right
Which one of these hills does the ball roll down in the least amount of time?
B. It is moving faster throughout.
On which of these hills is the speed of the ball greatest when the ball reaches the bottom of the slope?
The same, all have the same potential energy and the beginning and it goes to kinetic at the bottom.
On which of these hills is the speed increasing and the acceleration constant? Explain.
A. galileo said a ramp has a constant acceleration
Be picky and correct your friend who says "in free fall, air resistance is more effective in slowing a feather than a coin."
"Free fall means no air resistance"
Someone standing at the edge of a cliff throws a ball nearly straight up at a certain speed and another ball nearly straight down with the same initial speed. If air resistance is negligible, which ball will have the greatest speed when it strikes the ground below?
Both balls will hit with the same speed because there are no retarding forces act upon them.
Referring to the question above, which ball will hit the ground first. Explain.
The one you throw down. obviously.
A ball is thrown up with an initial speed of 30 m/s, How high does it go? When is the speed of the ball 0 m/s? How long is it in the air before hitting the ground? Show you work or explain your reasoning.
T | H | V 1. 45
0 0 30 ^ 2. 3
1 25 20 3. 6
2 40 10
3 45 0
4 40 10
5 25 20
6 0 30
Two balls are released simultaneously from rest at the left and of equal length tracks as shown. Which ball, track a or b, reaches the end of its track first.
B. because of the drop
Galileo discovered that uniform acceleration occurs for a ball rolling down an inclined plane. The plane below is tilted so that a ball picks up a speed of 4 m/s^2 each second; then its acceleration is a= 4 m/s^2. The positions of the ball are shown at 1 second intervals. Complete the blank for distance traveled and speeds.