PHYSICSPHYSICS

MOTIONMOTION

ENDURING UNDERSTANDINGS:ENDURING UNDERSTANDINGS:

• An object is in motion if its distance from a An object is in motion if its distance from a reference point is changing. reference point is changing.

• Speed is the distance traveled divided by the time Speed is the distance traveled divided by the time traveled. V = d traveled. V = d tt

• Acceleration is the rate at which velocity changes. Acceleration is the rate at which velocity changes.

INTERNATIONAL SYSTEM OF UNITSINTERNATIONAL SYSTEM OF UNITS

• The SI is based on the number 10. The SI is based on the number 10.

• The basic unit of length is the meter The basic unit of length is the meter

• The basic unit of volume is the liter The basic unit of volume is the liter

• The basic unit of mass is the gramThe basic unit of mass is the gram

• The basic unit of temperature is CelsiusThe basic unit of temperature is Celsius

THE METRIC LADDERTHE METRIC LADDER

kilokilo

hect

ohe

cto

deko

deko

met

er, l

iter

met

er, l

iter

cent

ice

nti

mill

im

illi

deci

deci

11 .1.1 .01.01 .001.00110101001001,0001,000

RELATIVE MOTIONRELATIVE MOTION• Relative Motion depends on your point of view. Relative Motion depends on your point of view.

• An object is in motion if its distance from a reference An object is in motion if its distance from a reference point is changing. point is changing.

Stand perfectly still. Are you in motion?Stand perfectly still. Are you in motion? From your point of view – no.From your point of view – no.

But if viewed from space, you would be moving at But if viewed from space, you would be moving at

about 1,000 mph with the rotation of the Earth!about 1,000 mph with the rotation of the Earth!

SPEEDSPEED• Speed is the distance traveled divided by the time.Speed is the distance traveled divided by the time.

speed = distance / timespeed = distance / time

• Average speed = total distance / total time: add all the Average speed = total distance / total time: add all the distances and divide by the total time.distances and divide by the total time.

32 km + 13 km = 45 km32 km + 13 km = 45 km 2 hrs + 1 hr = 3 hrs2 hrs + 1 hr = 3 hrs

• Instantaneous speed is the rate an object is moving at a Instantaneous speed is the rate an object is moving at a given instant in time.given instant in time.

45 km / 3 hrs = 15 km/hr45 km / 3 hrs = 15 km/hr

ACCELERATIONACCELERATION• Acceleration is any change in speedAcceleration is any change in speed

• Acceleration can be a decrease in speed, Acceleration can be a decrease in speed, increase in speed, or a change in directionincrease in speed, or a change in direction

Try it . . .Try it . . .• Sam rides his bike 4 miles to Sylvan’s house. It takes Sam rides his bike 4 miles to Sylvan’s house. It takes

him 20 minutes. What was Sam’s average velocity?him 20 minutes. What was Sam’s average velocity? V = 4 mi / 20 min V = 4 mi / 20 min V = .2 mi/minV = .2 mi/min

• What is Sam’s velocity in miles per hour?What is Sam’s velocity in miles per hour?

V = x = 12.0 mi/hrV = x = 12.0 mi/hr.2 mi.2 mi1 min1 min

60 min60 min 1 hr1 hr

• If Sylvan rode to Sam’s house averaging 15 mi/hr, how long If Sylvan rode to Sam’s house averaging 15 mi/hr, how long would it take him to go the 4 miles?would it take him to go the 4 miles?

T = = .2666hrT = = .2666hr

• How many minutes did it take Sylvan?How many minutes did it take Sylvan?

T = .2666hr x = 16 min T = .2666hr x = 16 min

• What was Sylvan’s speed in kilometers per hour? What was Sylvan’s speed in kilometers per hour?

x = 24.15 km/hrx = 24.15 km/hr

4 mi4 mi

15mi/hr15mi/hr

60 min60 min

1 hr1 hr

15mi15mi

1hr1hr

1.61km1.61km

1mi1mi