Question

Question 1

What does it mean when a camera captures a video 30 fps?

Group of answer choices

Camera captures video for 30 seconds

Camera captures 30 pictures each second to make a video

Camera captures 30 total pictures to make a video

Camera captures 30 videos in a row every second

Question 2

What does it mean when your lab partner says they dropped the ball?

Group of answer choices

The initial speed of the ball is zero and it is heading vertically downward

The are done dropping the ball

The inital speed of the ball is zero, but it can be heading in any direction

The initial speed of the ball can be anything, but it is heading vertically down

Question 3

What is the time interval between two consecutive pictures, if a camera takes 30 pictures every second?

Group of answer choices

10 seconds

1 second

1/30 second

30 seconds

Question 4

A Kinematic equation of motion tells us that, the time of fall of a ball dropped from a height (in meters) is approximately the square root of the (height/5).

Based on this information, how many seconds does it take for a ball dropped from 2-meters (a bit more than the height of a tall person) to hit the ground?

Group of answer choices

0.4 seconds

1 second

0.6 seconds

0.2 seconds

Question 5

In 0.5 seconds, how many frames can a 30-fps camera capture?

Group of answer choices

30 + 0.5 = 30.5

30/0.5 = 60

30*0.5 = 15

sqrt(30/0.5) = 7

Question 6

Surface computers, in our lab, have capstone video analysis software installed. It can split the video in frames (individual pictures). By marking a moving object in each frame, you can extract the position of the object over time. From the information, the software can make a position vs. time graph. It can internally estimate the velocity for each position and can also make a velocity vs time graph. But it doesn’t know how long one meter is. So, you need to hold a meter stick on the frame so that you can tell the software, how much is one meter.

Suppose you used two cameras, a 30-fps, and 60-fps, to capture a video. Approximately, how many positions one can expect in the position vs. time graph in capstone software from a 0.5-second long video using the 30-fps and 60 fps camera respectively. ( How man data points in 0.5 seconds?)

Group of answer choices

30, 60

15, 30

30, 15

60, 30

Question 7

Suppose you found your cell phone camera has a larger frame rate and better-quality video than the surfaces. You decided to capture the video with your cell phone. How would you transfer the video from your phone to surface computers for further analysis?

Group of answer choices

All of the above methods should work but depends on what option is available

Upload video to my google drive account from phone and download to the computer

Connect my charger usb-cable to the surface

Upload video to one drive and download video on computer

Question 80 pts

Slower the frame rate (15- fps is slower than 30-fps), fuzzier the object looks in each frame of the video. It becomes harder to locate the position of the ball. It introduces larger uncertainty in position and therefore the uncertainties propagate to velocity and all the way to acceleration. Remember we want to find acceleration of falling object and compare with the accepted value 9.8 m/s2. How would you keep track of the uncertainties? Please write down the response of this question on your notebook.

Answer 1

1. fps is an abbreviation for Frames per second. Hence 30fps means the Camera captures 30 Pictures each second to make a video.

2. Since the ball is being dropped, it means the initial speed of ball is zero and it is heading vertically downward.

3. Since the camera is taking 30 pictures every second, thus, time taken for one picture

=   (1/30)=0.033 sec. This is the time between two pictures taken.

4. The time fall is given as t= (h/5)^1/2,

             Thus, for h=2 meters, time of fall = (2/5)^1/2 = 0.63 ~ 0.6 seconds

5. Since 30fps means 30 frames per second, hence, in 0.5 seconds,

No. of frames captured = 30*0.5 = 15 Frames

6. Since a position vs time graph gives each frame a coordinate, thus, using a 30 fps and a 60 fps camera for a 0.5 second will give

30*0.5=15 ;    60*0.5=30;

Thus There will be 15 and 30 data points in 0.5 seconds using a 30 fps and 60 fps camera respectively.

7. All of the methods should work, i.e. via usb, google drive or one drive.