| 1. |
How much momentum does a 100. kg fullback
have running at 9.50 m/s.
|
|
p = mv = 100. kg x 9.50 m s -1 = 950. kg
m s -1
|
|
|
| 2. |
What is the change in momentum if a 40.0 g
superball hits a wall at 25.0 km/h and rebounds at 180o with a
speed of 20.0 km/h?
|
|
25.0 km 1000
m 1
h
20.0 km 1000
m 1 h
------------ x ----------- x ----------- = 6.94
m/s
------------ x ----------- x ----------- = 5.56 m/s
1
h
1 km 3600
s
1
h
1 km 3600 s
/\v = v2 - v1
= -5.56 m/s - 6.94 m/s = -12.50 m/s
/\p = /\mv = 0.0400 kg x (
-12.50 m/s ) = -0.500 kg m s -1
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|
|
| 3. |
Water coming out of a hose at 2.0 kg/s and
30. m/s strikes a wall and falls straight down without splashing
back. What is the force exerted by the water on the wall?
|
|
Every second 2.0 kg of water hit the wall and comes
to a rest.
/\p 2.0 kg x ( 0. m/s -
30. m/s )
 F = ----- =
-------------------------------------- = -60.
N This
is the force on the water
/\t
1.0 s
60. N is the force of the water on the wall.
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|
|
| 4. |
A 4.00 N force is applied for 5.00 s in the
same direction a 300. g baseball is all ready moving at 50.0 m/s.
What is the acceleration and new velocity of the baseball?
|
|
F
4.00 N
F =
ma => a = ------- = ------------- =
13.3 m s -2
m 0.300 kg
v = v1 + at = 50.0 m s -1
+ 13.3 m s -2 x 5.00 s = 116.5 m/s
|
F =
----