## Monday, 27 October 2014

### speed , velocity and displacement problems

1.   A car is traveling at 30. meters per second.  How much distance does it cover in 1 second?
In 2 seconds?      In a minute?

2.  a/   A jet ski moves 280 meters north in 6.3 seconds.   What is its speed?

b/   What is its velocity?

3.   a/  A bicycle moves at 15 m/s east for 2.5 seconds.   What distance does it travel?

b/    What is its displacement?

4.   If a car travels at 35 m/s, how much time does it take to travel 2 km?   (Hint: You MUST change the km to meters before doing the math!)

5.   Two cars, each traveling at 50 mph, are heading in opposite directions.   Compare their speeds and velocities.

6.  See page 1 of the Reference Tables to find the speed of sound in air at STP =  ________ m/s
How far does sound travel in air in 5.0 s?

7.   See page 1 of the Reference Tables to find the speed of light in a vacuum =  ______________ m/s
How much time does it take light to travel 30 cm (30 x 10-2 m), which is about 1 foot?

8.  a/  If car A travels twice as far as car B in the same time, how does vA compare to vB?
What if car A travels three times as far?
Is speed related directly or inversely to distance (if time is constant)?

b/   If car X takes twice as much time as car Y to travel the same distance, how does vX compare to vY?
What if car X takes three times as much time?
Is speed related directly or inversely to time (if distance is constant)?

9.   A car travels 90. meters due north in 15 seconds.   Then the car turns around and travels 40. meters due south for 5.0 seconds.
a/   Remember that average speed = distance / time.    Find the average speed in the first 15 seconds alone.

b/  Now find it for only the last 5.0 seconds.

c/   Now find it for the entire 20. seconds.    (Hint: Use total distance.)

e/  Find the average velocity in the first 15 seconds.  Remember that average velocity = displacement/time, so your answer will have a direction.

f/    Now find average velocity during the last 5.0 seconds.

g/     Now over the entire 20. seconds.   (Hint: Use the resultant displacement over the entire 20 s.)

h/   Why is your average velocity (part g/) so different from your average speed (part c/)?