CHAPTER 6. MOTIONIN TWO DIMENSIONS 6.5
(b) according to someone outside the train?
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(1.) 01s6 (2.) 01s7
Chapter 6 — Summary
See the summary presentation ( Presentation: VPnmi at http://www.everythingscience.co.za)
- Projectiles are objectsthat move through the air.
- Objects that move up and down (vertical projectiles) on the earth accelerate with
a constant acceleration g which is approximately equal to 9,8 m·s−^2 directed
downwards towards thecentre of the earth.
- The equations of motion can be used to solve vertical projectile problems.
vf = vi+ gt
Δx =
(vi+ vf)
2
t
Δx = vit +
1
2
gt^2
v^2 f = vi^2 + 2gΔx
- Graphs for vertical projectile motion are similar to graphs for motion at constant
acceleration. If upwardsis taken as positive the Δx vs t, v vs t ans a vs t graphs
for an object being thrown upwards look like this:
h (m)
t (s)
tm tf
hm
(a)
0
v (m·s−^1 )
t (s)
tm
tf
0
vi
vf
(b)
g
a (m·s−^2 )
t (s)
(c)
0
- Momentum is conserved in one and two dimensions.
p = mv
Δp = mΔv
Δp = FΔt
