Motion
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- Pages: 14
Motion Everything is in motion and there are only two possibilities. 2. Constant Velocity v = zero or v = a value 2. Changing Velocity which is called acceleration
Velocity • velocity is the rate at which position changes or displacement changes • V = ∆d/∆t • Velocity is the slope of d vs t graph
Velocity Displacement (m)
Time (s)
0
0
20
1
40
2
60
3
80
4
DEB – Sketch the Graph. What is the Slope?
Average vs Instantaneous • Average speed is the total distance divided by the total time. – This is over a long time interval. • Instantaneous speed is how fast are you going now ie. - speedometer, radar gun, slope at a point - This is over a short time interval, with t approaching 0
Average Velocity • You drive your car 200 miles in 5 hours. What is your average velocity? H-ITT A) 0 B) 20 C) 40 D) 100 mph • But did you at any time travel exactly 40 miles per hour? • H-ITT A) Yes B) No C) impossible to tell
H-ITT
Graph of d vs t
B)25 mph 200
C) 50 mph
150
D)100 mph D) 150 mph
d in 100 miles 50
1
2 t in hours
3
4
5
H-ITT
Graph of d vs t
B) -150 mph
C) -100 mph
200
D) -50 mph
150
D) -25 mph
d in miles100
E) 0
50
1
2 t in hours
3
4
5
Instantaneous Velocity • How could we get the instantaneous velocity of an air track glider or lab cart using a flag?
Instantaneous Velocity • Time the flag as it passes through the photogate. Measure the length of the flag. • V = d flag / t flag • What happens as the flag gets
Acceleration •
acceleration is the rate at which velocity changes • a = ∆v/∆t • a = (vf – vi)/(t2 – t1)
• vf = vi + at • The acceleration is the slope of v vs t graph
Acceleration • H-ITT A) 0 B) 8 C) 40 D) 200 E) 0.13
40 V (m/s)
t (s)
5
Acceleration • The slope of a velocity vs time graph is acceleration a = ∆v/∆t • If there is no slope, the acceleration is zero = constant velocity • If there is a positive slope, the velocity is getting more positive. • If there is a negative slope, the velocity is getting more negative. • The area under v vs t graph is displacement
Acceleration • H-ITT A) 0 B) 8 C) 40 D) 200 E) 0.13
40 V (m/s)
t (s)
5
Acceleration • H-ITT A) 0 B) -10 C) -30 D) 20 E) 25
40 V (m/s) 10
t (s)
3
5
Velocity • velocity is the rate at which position changes or displacement changes • V = ∆d/∆t • Velocity is the slope of d vs t graph
Velocity Displacement (m)
Time (s)
0
0
20
1
40
2
60
3
80
4
DEB – Sketch the Graph. What is the Slope?
Average vs Instantaneous • Average speed is the total distance divided by the total time. – This is over a long time interval. • Instantaneous speed is how fast are you going now ie. - speedometer, radar gun, slope at a point - This is over a short time interval, with t approaching 0
Average Velocity • You drive your car 200 miles in 5 hours. What is your average velocity? H-ITT A) 0 B) 20 C) 40 D) 100 mph • But did you at any time travel exactly 40 miles per hour? • H-ITT A) Yes B) No C) impossible to tell
H-ITT
Graph of d vs t
B)25 mph 200
C) 50 mph
150
D)100 mph D) 150 mph
d in 100 miles 50
1
2 t in hours
3
4
5
H-ITT
Graph of d vs t
B) -150 mph
C) -100 mph
200
D) -50 mph
150
D) -25 mph
d in miles100
E) 0
50
1
2 t in hours
3
4
5
Instantaneous Velocity • How could we get the instantaneous velocity of an air track glider or lab cart using a flag?
Instantaneous Velocity • Time the flag as it passes through the photogate. Measure the length of the flag. • V = d flag / t flag • What happens as the flag gets
Acceleration •
acceleration is the rate at which velocity changes • a = ∆v/∆t • a = (vf – vi)/(t2 – t1)
• vf = vi + at • The acceleration is the slope of v vs t graph
Acceleration • H-ITT A) 0 B) 8 C) 40 D) 200 E) 0.13
40 V (m/s)
t (s)
5
Acceleration • The slope of a velocity vs time graph is acceleration a = ∆v/∆t • If there is no slope, the acceleration is zero = constant velocity • If there is a positive slope, the velocity is getting more positive. • If there is a negative slope, the velocity is getting more negative. • The area under v vs t graph is displacement
Acceleration • H-ITT A) 0 B) 8 C) 40 D) 200 E) 0.13
40 V (m/s)
t (s)
5
Acceleration • H-ITT A) 0 B) -10 C) -30 D) 20 E) 25
40 V (m/s) 10
t (s)
3
5
