# On your paper, graph the following: D (m) T (sec) 00 57 57 10 14 15 21.

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On your paper, graph the following: D (m) T (sec) 00 57 57 10 14 15 21

A distance-time graph which is a straight line indicates constant speed. In constant speed, the object does not speed up or slow down. The acceleration is zero.

D (m)T (s) 00 51 202 453 804 1255

0 1 2 3 4 5

A graph that curves on a distance-time graph shows that the object is accelerating

Speed = Distance ÷ Time D_ S T Example: A car travels 300km in 6 hours. What is the speed of the car?

Speed = distance ÷ time Speed = 300km ÷ 6 hours Speed = 50km/hr

1. How far can a plane travel if it flies 800km/hr for 9 hours? 2. How long does it take a ship to go 500 km if it travels at a speed of 50km/hr?

1. D S T D 800 9 800km 9hrs = 7200km hr

2. D S T 500 50 T 500km ÷ 50km = 10 hrs hr

Describe the motion of the object as shown in the graph. From 0-8 sec, constant speed: (25 m/sec); From 8-12 sec, no motion; From 12-16 sec, acceleration; From 16-20 sec, constant speed

Using the distance-time graph from the last frame, draw a speed time graph. First fill in the table below: Average Speed (m/s) Time (sec) ____0 to 8 ____8 to 12 ____12 to 20 25 0 37.5

Constant speed will be a horizontal line on a speed time graph. If the speed decreases, the line will slant down. If the speed increases, the line will slant up.

Change in velocity Can be change in speed or direction Acceleration = V/ T V at

A roller coasters velocity at the top of a hill is 10m/s. Two seconds later it reaches the bottom of the hill with a velocity of 26m/s. What is the acceleration of the roller coaster?

Acceleration = V/ T a = 26m/s – 10m/s 2 s a = 16m/s 2s a = 8m/s/s or 8m/s 2

Negative acceleration Example: A car slows from 60mi/hr to 20mi/hr in 4 seconds. What is its acceleration? Acceleration = V/ T Acceleration = Vf – Vi t a = 20mi/hr – 60mi/hr 4 s a = -40mi/hr 4s a = -10mi/hr/s

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