12+
16 дней назад
Wizarding Secrets
Introduction of acceleration, both definition and calculation. Designed for Science 10 and Physics 11.
http://www.BCLearningNetwork.com
.0:00we've talked lots about scalars and0:02vectors so far and we've established0:04that distance is a scalar quantity0:07well displacement is a vector quantity0:09speed is a scalar quantity which is0:13based on distance and velocity is a0:16vector quantity which is based on0:18displacement our newest addition here is0:22acceleration and acceleration is a0:25vector quantity and it's based on0:27velocity while velocity is the rate of0:31change of displacement acceleration is0:35the rate of change of velocity our0:39equation for calculating acceleration is0:41as follows a equals Delta V over delta T0:46if we compare it with our equation for0:49velocity will see that they're pretty0:51darn similar when we say that velocity0:54is the rate of change of displacement we0:56simply take displacement and we divided0:59by the change in time in the same way1:02when we say that acceleration is the1:05rate of change of velocity we take our1:08change in velocity and we divided by the1:11change in time a very similar idea1:14velocity is the rate of change of1:18displacement that is how fast the1:20displacement is changing acceleration is1:24the rate of change in velocity in that1:27how fast velocity is changing1:29acceleration is a little more difficult1:33to visualize rather than reading the1:36speedometer in a car1:38acceleration is more how fast the1:40speedometer readout or needle is1:42changing at this point you deserve a1:46congratulations you've entered into1:48second-order rates1:50this is really getting into second order1:53derivatives and calculus and advanced1:55branch of mathematics so well done if1:57you can get the concept of acceleration2:00clearing your head this point you're2:02laughing and that you've already2:04established yourself nicely in both2:06physics and calculus concepts this is2:09the land of Isaac Newton certainly one2:12of the greatest intellects inhuman here2:13three so nicely done2:17so let's do an acceleration example2:20while skiing Hanna starts down a hill2:23from rest after 20 seconds she's going2:2630 km/h what was our average2:30acceleration during this run2:32first of all let's get some things we2:34know listed down here the initial2:37velocity well let's see she started from2:40rest so the i would have to be zero the2:44final velocity VF is 30 km/h the initial2:50and final time well we can just say that2:53delta T the change in time is 20 seconds2:57that is the time of the trip we are2:59considering here now we could just jump3:02into the equation but first of all let's3:05take a quick look at the units we have a3:08mix of units here we have kilometers and3:11hours and seconds now what we want in3:16our final answer for units is always a3:18bit of a question if there's some way of3:21indicating what units are best in the3:24final answer then3:25great maybe a multiple choice and you3:27see what units are being used otherwise3:29it's good practice to produce your3:32answer in the standard SI units that is3:36units that involve only meters and3:39seconds so let's do a unit conversion3:44here the 30 km/h could be changed into3:48$OPERAND m/s then everything else would3:50be $OPERAND meters and seconds again we3:53know that there is 1000 meters in a3:56kilometer and we want to cancel out the4:00kilometers because we want to be left4:01with meters so we'll put the one4:04kilometer in the bottom and the 10004:07meters on the top now for the time we4:11know that there's 3600 seconds in an4:14hour so we have the hour on the bottom4:17here so to cancel it will put the hour4:20on the top here and that leaves the 36004:23seconds on the bottom the kilometers4:26cancel out perfect4:28and we're left with meters for our final4:30answer excellent the hours now they4:35cancel out and again we're left with4:38seconds on the bottom4:40perfect it confirms that we set up the4:43conversions correctly so now we can put4:46the calculator and 30 x 1000 because4:50when thousands on top and then we'll4:53divide by 3600 because the 3600 on the4:56bottom and we're left with 8.33 m/s with5:02a little rounding so 30 km/h change to5:07standard units is the exact same as 8.335:12m/s ok so back to our question now we5:16have all of our units all cleared up and5:19it's time to pull out our equation a5:22equals Delta V over delta T would do5:25nicely5:26r delta T was 20 seconds5:30r delta v is the change in velocity and5:33we went from zero to 8.3 m/s so the5:37Delta V or V final minus the initial is5:418.3 m/s and we divide these and with a5:46little rounding we get 0.42 now what5:50about the unit's here we have m/s on the5:53top and seconds on the bottom and if we5:56combine these it gives us m/s squared6:00that is two seconds on the bottom the
, чтобы оставлять комментарии
