Transcript SPEED depends on DISTANCE and TIME

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When an object change position over time relative
to a reference point, the object is in MOTION
Is the DISTANCE traveled by and object divided by
the TIME taken to travel that distance
SPEED depends on DISTANCE and
TIME
Actual Speed
Average speed
SPEED depends on DISTANCE and
TIME
- What is your average speed is you take 0.5 h to
jog 4 000 m?
- If the average speed of a car is 110 km/h, how
long will it take the car to travel 715 km?
VELOCITY and SPEED
The VELOCITY is constant only if the speed and direction
don’t change (straight line)
The VELOCITY changes only if SPEED OR DIRECTION
changes.
Both cars have the same SPEED, but different VELOCITY
COMBINING VELOCITY
Person’s
resultant
velocity
14 m/s
Two velocities that are in opposite directions
REMEMBER
WHY!
16 m/s
Two velocities that are in the same direction
Person’s
resultant
velocity
COMBINING VELOCITY
14 m/s
Two velocities that are in opposite directions
15 m/s east
=
14 m/s east
1 m/s west
15 m/s east – 1 m/s west = 14 m/s east
SPEED and ACCELERATION
Acceleration is the rate at
which velocity changes
TRY IT!
Acceleration is not only how much velocity changes but also how fast
velocity changes.
The faster the velocity changes, the greater the acceleration is.
T or F??
1.
2.
3.
If you slow down on your bicycle, you accelerate
If you ride your bicycle at a constant speed, you cannot accelerate
Changing the speed and changing the direction of your bicycle are both
example of acceleration
Diagram the following situations:
1.
2.
3.
You are riding your bike at 9 km/h. Ten minutes later, your speed is 6
km/h
You ride your bike around the block at a constant speed of 11 km/h
You ride your bike in a straight line at a constant speed of 10 km/h
The NET FORCES on an object tells you whether the forces on an object are
balanced or unbalanced
Unbalanced Forces: necessary to cause a
nonmoving object to star moving
READING: 124 – 133
HOMEWORK NEXT WEEK : 134 – 135
WORKBOOK: 86 – 98
(MID TERM HOMEWORK)