Practice Quiz 0620

Sketch an approximate graph of the velocity of a ball on the ramp you used in the mini experiment vs. clock time.

Sketch an approximate graph of the position of a ball on the ramp you used in the mini experiment vs. clock time.

Give the average rate at which position changes with respect to clock time, from one end of the ramp to the other.

Estimate from your graph the average rate at which position changes with respect to clock time.

Time down ramp:  4.2 half-cycles of a 22 cm pendulum.

22 cm pendulum:  period = .2 sqrt(L) = .2 sqrt(22) = .2 * 4.7 = .94, meaning each cycle takes .94 seconds. 

How long to get down the ramp?

We know how many half-cycles and how many seconds per cycle.  We can either

• find the time of a half-cycle and multiply by the number of half-cycles or
• find the number of cycles and multiply by the time per cycle.

We get 2.1 cycles at .94 sec per cycle or 1.97 sec.

Alternatively we get 4.2 half-cycles at .47 sec per half-cycle of 1.97 sec.

For the ramp demonstrated in class position changed from y = 32 cm to y = 2 cm between clock times 0 and 2 s.

Average rate of position change with respect to clock time is change in position / change in clock time.

We first find change in position and change in clock time:

• Change in position is

later position - earlier position = 32 cm - 2 cm = -30 cm.

• Change in clock time is

later clock time - earlier clock time = 2 sec - 0 sec = 2 sec.

... these notes are still to be completed ...