Answer key for the plug and chug problems on page 26 and 27

Plug and Chug

1. s=d/t
so s = 140/5
s = 28km/h

2. a. s= d/t
so s = 4/.5;
s = 8km/h
Where did .5 come from? It's half of an hour and we are calculating in km/h.


2. b. s = d/t
so 8 = d/1
8 = d

3. a = v/t
a = 100/10
a = 10 km/h/s

4. v=at
v = 2m/s/s X 10s
v = 20 m/s

5. v = at
v = 5m/s/s x 3 s
v = 15 m/s

6. v=a
v= 10m/s/s x 1.5
v = 15

7. Instant speed v = at
v = 10m/s/s x 6 s
v = 60 m/s
Where did 10 m/s/s come from? That's the acceleration of the object due to gravity.

Average Speed
If 60 m/s is the final speed and 0 is the starting speed then
(60 + 0)/2 = 30 m/s To find the average I've added the speeds and divided by the number of data points I used, in this case, two data points.

Distance Fallen
d=1/2at^2
d = 1/2 10 (6)^2
d= 5 x 36
d = 180

8. Speed
v=at
v= 10 x 8
v = 80

Distance fallen
d=1/2at^2
d=1/2 x 10 x (8)^2
d = 5 x 64
d = 320