#### Acceleration

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Acceleration

Principles of Physics
motion along a straight line path, motion in
one dimension
Which way are you headed?
How far did you go?
How fast are you going?
Is your speed changing?
Acceleration
Rate at which speed changes
In other words, speeding up or slowing down
Measured in meters per second2
More commonly stated as “the object goes
from 0 to 40 m/s in 8 s”
Acceleration is calculated
2)
a
=
acceleration
(m/s
vf vi
a
vf = final velocity (m/s)
t
vi = initial velocity (m/s)
v f v i at
t = time (s)
Acceleration is a vector quantity
+ when speeding up
- when slowing down (deceleration)
Blue and green cars accelerate, the red car travels with a constant velocity.
At rest
Starting from rest → vi =0
Initially at rest
Comes to rest → vf = 0
1. A particle has a constant acceleration of 2.0 m/s2.
Calculate the time required for the particle to accelerate
from 8.0 m/s to 28 m/s.
Givens:
a = 2.0 m/s2
vf = 28 m/s
vi = 8.0 m/s
t=?
vf = vi +at
28 m/s = 8.0 m/s + 2.0 m/s2 (t)
28 m/s - 8.0 m/s = t
2.0 m/s2
10 s = t
2. A car travelling at 32 m/s comes to rest in 30 s.
Calculate the acceleration of the car.
Givens:
a=?
vf = 0 m/s
vi = 32 m/s
t = 30 s
vf vi
a
t
0 32m / s
a
30s
a 1.07m / s 2
If you do not know the final velocity of an
object, but do know the displacement of the
object you can calculate the acceleration using:
d = vit + ½ at2
d = displacement (m)
vi = initial velocity (m/s)
t = time (s)
a = acceleration (m/s2)
3. A car starting from rest accelerates at 4 m/s2 for 6 s.
Calculate the car’s displacement.
Givens:
vi = 0 m/s
a = 4 m/s2
t= 6 s
d=?
d = vit + ½ at2
d = 0m/s (6s) + ½(4 m/s2 )(6s)2
d = 72 m