Question

write all work in your notebook or cut and attach (tape or glue) into your notebook neatly

1. is the objects motion constant? explain.
2. what is the velocity during the first 4 seconds?
3. what is the velocity during the last 6 seconds?

drawing position - time graphs
problem 1: a car travels 6 meters in 3 seconds. it then stops for 5 seconds. then the car goes 2 meters in 2 seconds.
position - time graph
position (m)
0 1 2 3 4 5 6 7 8 9 10
time (s)
a. what is the velocity of the car for the first 3 seconds?
b. what is the velocity of the car from times 3 - 8 seconds?
c. during which time is the car moving faster, 0 - 3s or 8 - 10s? how could you know this without calculating the velocity?
problem 2: a car travels 8 meters in 2 seconds. it stays motionless for 3 seconds. it then goes - 5 meters in 5 seconds.
position - time graph
position (m)
0 1 2 3 4 5 6 7 8 9 10
time (s)
a. what is the velocity of the car for the first 2 seconds?
b. what is the velocity of the car from times 2 - 5 seconds?
c. what is the velocity of the car from times 5 - 10s?
problem 3: a car travels 5 meters in 2 seconds. the car then stays motionless for 2 seconds. it then moves 5 meters in the opposite direction in 4 seconds. last, the car moves forward at 3m/s for 2 seconds.
position - time graph
position (m)
0 1 2 3 4 5 6 7 8 9 10
time (s)
a. what is the velocity of the car for the first 2 seconds?
b. what is the velocity of the car from times 4 - 8 seconds?
c. how far did the car move from 8 - 10s?

Explanation:

and $\Delta t = 2$ s. So, $v=\frac{5}{2}=2.5$ m/s

b.

Step1: Analyze motion from 4 - 8 seconds

The car moves 5 meters in the opposite direction in 4 seconds. $\Delta x=-5$ m and $\Delta t=8 - 4 = 4$ s. Then $v=\frac{-5}{4}=-1.25$ m/s

c.

Step1: Use the formula $d = vt$

The car moves forward at $v = 3$ m/s for $t=10 - 8 = 2$ s. Using the formula $d = vt$, we get $d=3\times2 = 6$ m

Answer:

Problem 1:
a. 2 m/s
b. 0 m/s
c. The car is moving faster from 0 - 3 s because the slope of the position - time graph is steeper.
Problem 2:
a. 4 m/s
b. 0 m/s
c. - 1 m/s
Problem 3:
a. 2.5 m/s
b. - 1.25 m/s
c. 6 m