Speed, Velocity
Good morning
Speed and Velocity are common terms in our language.
We all marvel with Usain Bolt records, and wonder how a person can be so fast.
In step of Speed and Velocity we talk about how fast or slow is an object. Now
you know how to calculate how much fast an object moves.
Let refresh the concepts
Speed, represented with a capital S, is defined as how
fast and objects travel. Speed is how many meters an object travels in a unit
of time. Speed does not depend on
direction. Speed is calculated using the following formula
Speed= distance÷time
S=d÷t
The units for speed are m/s
Velocity, represented with a lowercase italics v, is defined as a speed with direction.
Velocity does depend on direction.
For velocity we take in consideration the direction in which the object move
and its displacement. For calculate velocity use the following formula
v=displacement÷time
v=
ΔX÷t
Remember, that using these two formulas we can also calculate the other two magnitudes involved
Now we INVITE you to solve the following problems.
1. NASCAR driver, Jeff Gordon, has a car that is one of
the fastest on the circuit. If it travels 965.61 kilometers in 4 hours, what is
his cruising speed?
2. The fastest car on Earth, a German-made Thrust SSC,
would win every NASCAR race in America. If it takes 0.5 hours (30 minutes) to
travel 611.55 kilometers, what is its speed?
3. The fastest train on Earth, the TGV from
France, can travel at faster speeds than trains in the United States. During a
speed test, the train traveled 1287.45 kilometer in 2.5 hours. What is its
speed?
4. Spirit of Australia, a hydroplane
boat, made speed records by traveling 384.63 kilometers in 0.75 hours (45
minutes). What is its record-breaking speed?
5. The fastest plane ever made, the Lockhead SR71,
was able to travel 3540.56 kilometers per hour. Based on this speed, how
far could it travel in:
a. 2 hours?
b. 3 hours?
c. 5 hours?
6. You and your friend each drive 50.0 km. You
travel at 90.0 km/h. Your friend travels at 95 km/h. How long will
your friend be waiting for you at the end of the trip?
7. With an average speed of 67m/s, how long does it take
a falcon to dive to the ground along a 150m path?
8. A world record of 274m/s for the fastest jet engine
car has the following measurements. The driver makes two runs through the
course, one in each direction. The car first travels from left to right
and covers a distance of 604m in 2.19s. The car then reverses direction
and covers the same distance in 2.22s. From these data, determine the
average velocity for each run.
9. During a trip, a bus travels 11km with an average
velocity of 21m/s, but then travels 1.0km at a smaller velocity of 4.2m/s, due
to the presence of highway construction. Determine the average speed of
the bus for the entire trip.
10. Sound travels at a constant speed of 343m/s in
air. Approximately how much time (in seconds) does it take for the sound
of thunder to travel 1609m?
11. A car is travelling at a constant speed of
27m/s. The driver looks away from the road for a 2.0s to tune in a
station on the radio. How far does the car go during this time? 54m
12. A three toed sloth is the slowest moving land
mammal. On the ground, the sloth moves at an average speed of 0.037m/s,
considerably slower than the giant tortoise, which walks at 0.076m/s. After
12 minutes of walking, how much further would the tortoise have gone relative
to the sloth?
13. A sky diver, with parachute unopened, falls 625m in
15.0s. Then she opens her parachute and falls another 356m in 142s.
Using a position time graph calculate what is her average velocity (both
magnitude and direction) for the entire fall? 6.2m/s down
14. A car makes a 60.0 km trip with an average velocity of
40.0km/h in a direction due north. The trip consists of three
parts. The car moves with a constant velocity of 25km/h due north for the
first 15km, and 62km.h due north for the next 32km.
a) draw a position time graph of this situation and b)
With what velocity does the car travel for the last 13km segment of the trip.
15. A motorbike travels 200 km
in 2 hours and 15 minutes. How fast is it going?
16. What distance is travelled
by a car going 80 km/h in a time of 4 hours 30 minutes?
17. The World Snail Racing
Championships have been held in the English village of Congham,
Norfolk since the 1960s. (Despite the international title, "foreign
snails are not allowed.") The contestants are placed at the center of a
circular table covered with a damp tablecloth and race outwards 13 inches
(33 cm) towards the finish line. A contestant known only as Archie set the
current world record of 2 minutes 20 seconds in 1995. Determine Archie's speed in m/s and
km/h.
