On your paper, graph the following:◦ D (m) T (sec)

0 0 5 7 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) 0 0 5 1 20 245 380 4125 5

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 ÷ timeSpeed = 300km ÷ 6 hoursSpeed = 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

D800 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 2025

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 a t

A roller coaster’s 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/ ∆Ta = 26m/s – 10m/s

2 sa = 16m/s

2sa = 8m/s/s or 8m/s2

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 sa = -40mi/hr

4sa = -10mi/hr/s