Distance v. Displacement
A runner travels 400 m around a circular track and ends where they started. What’s their displacement?
0 m
Formula for average acceleration?
a=vf-vi/t
Define a resultant vector.
The overall vector found by combining two or more vectors. (ans vary)
How many kinematic equations are there?
4
Which formula finds velocity when you know distance and time?
v=d/t
You walk 5 m east, then 12 m north. What is your total distance traveled?
17 m
A car speeds up from 10 m/s to 30 m/s in 4 seconds. What’s its average acceleration?
5 m/s2
A plane flies 100 km north, then 100 km east. What is the resultant?
141 km at 45° east of north
What variable do all kinematic equations assume is constant?
Acceleration
Which formula do you use to find acceleration from two velocities and time?
a = vf-vi/t
You walk 5 m east and 12 m north. What is your displacement?
13 m
A ball rolls to a stop from 20 m/s in 5 s. What’s its acceleration?
-4m/s2
When two vectors are in opposite directions, how do you find the resultant?
Subtract the smaller from the larger and keep the direction of the larger.
Name one of the four kinematic equations.
(ans vary)
Which kinematic equation doesn’t include time?
vf2=vi2+2ad
You walk 30 m east, then 40 m west. What’s your displacement?
10 m west
Describe what negative acceleration means.
The object is slowing down
A boat moves 8 km/h east while a current pushes it 6 km/h south. What’s the resultant velocity?
10 km/h at 36.9° south of east
A car accelerates from rest at 3 m/s² for 6 s. How far does it travel?
54 m
Which equation finds distance when you know initial velocity, acceleration, and time?
d=vit+1/2at2
Explain how distance and displacement could be the same value for one trip but not for another.
They’re the same when you move in a straight line; different when direction changes.
A rocket goes from rest to 250 m/s in 25 s. What is its acceleration?
10 m/s2
DAILY DOUBLE:
Everyone choose an amount to wager!
A plane flies 250 km at 30° north of east, then turns and flies 180 km at 45° south of east. Find the magnitude and direction of the plane’s resultant displacement.
A ball is thrown upward at 20 m/s. How long until it reaches its highest point?
2.04 s
Which equation would you use if you know only vi, vf, and t?
d=1/2(vi+vf)t