Speed

:: | Instantaneous Speed | ::

Speed

Speed is related to time and distance. When you drive a car down a 50 km road in 1 hour we say you are driving at a speed of 50km/h.

Average Speed

Average speed is ythe total distance divided by the total time for a trip.

The equation would look something like this:

 The Symbol or Equation Explaination Vav = d/t This is the equation for average speed **remember this equation This is the symbol for "change in" also known as delta d This means the change in distance, "elapsed distance" or "distance" d = d2 - d1 d1 is where the first measured distance and d2 in the second measured distance. d1 is usually 0 t This is the "change in time," elapsed time," "period of time,"t or "time." t = t2 - t1 t1 is the first time measurement and t2 is a later time measurement. t1, the start time, is often zero.

Quantity symbols

These are italic letters used to represent quatities like distance, time and speed in a scientific equation. A letter can be used again to represent another quantity, for example d can mean distance, diameter, or density.

Instantaneous Speed

Instanteous is the speed of an object at a particular instant of time. Intrustments that measure instantaneous speed are speedometers and "radar guns.".

Constant Speed

Constant speed is when instantaneous speed stays uniform for a period of time. Cars and airplanes alike have devices called cruise control to keep a constant speed.

 Sample problem 1 The distance from Simran's house to his school was 4.7 km. He walked to his school in .25 hours, wut was his average speed? Step 1: State the given information. d =4.7 km t = .25 Hours Vav = ? Step 2: State the equation and modify the equation when needed Vav = d/t Step 3: Answer the question filling in the given information into equation. Vav = 4.7km/.25hours Vav = 19 km/h (**remember to following the Certainty/Significant Digit Rule) Step 4: Write the answer in sentence form Simran's average walking speed to his school was 19 km/h (I guess Simran was late)
 Sample problem 2 Your going to a skiing hill in Geneva...and you decide to go down "The Hill of Terror". You finish the hill in a record 3 minutes (without breaking a bone might i add)at a speed of 76km/h . What was the total distance you travelled? Step 1: State the given information d = ? t = 3 minutes = 3min x 1/60 = 0.05 hours Vav = 76Km/h Step 2. State the question and modify the equation when needed Vav = d/t (we need to find d so we must re arrange the equation) d = Vavt Step 3: Answer the question filling in the given information into equation. d = 76km/h x 0.05 hours d = 3.8 km Step 4: Write the answer in sentence form Therefore you travelled a total of 3.8 km in 3 minutes down the "The Hill of Terror".
 Sample problem 3 A base ball player runs the 50m bases at a speed of 30km/h after hitting a home run. In how much time did he do this? Step 1: State the given information d = 50m t = ? Vav = 30 m/h Step 2. State the question and modify the equation when needed Vav = d/t (we need to find t so we must rearrange the equation) t=Vav/d Step 3: Answer the question filling in the given information into equation. t=30m/h / 50 t=1.7hours Step 4: Write the answer in sentence form The player ran 50m in 1.7 hours. What can he say he was joyeous he finally hit a home run that we walked the bases....very slowly.

Continue to the next lesson: ::Distance - Time Graphs::