Answer:Bruce is knocked backwards at
14
m
s
.
Explanation:
This is a problem of momentum (
→
p
) conservation, where
→
p
=
m
→
v
and because momentum is always conserved, in a collision:
→
p
f
=
→
p
i
We are given that
m
1
=
45
k
g
,
v
1
=
2
m
s
,
m
2
=
90
k
g
, and
v
2
=
7
m
s
The momentum of Bruce (
m
1
) before the collision is given by
→
p
1
=
m
1
v
1
→
p
1
=
(
45
k
g
)
(
2
m
s
)
→
p
1
=
90
k
g
m
s
Similarly, the momentum of Biff (
m
2
) before the collision is given by
→
p
2
=
(
90
k
g
)
(
7
m
s
)
=
630
k
g
m
s
The total linear momentum before the collision is the sum of the momentums of each of the football players.
→
P
=
→
p
t
o
t
=
∑
→
p
→
P
i
=
→
p
1
+
→
p
2
→
P
i
=
90
k
g
m
s
+
630
k
g
m
s
=
720
k
g
m
s
Because momentum is conserved, we know that given a momentum of
720
k
g
m
s
before the collision, the momentum after the collision will also be
720
k
g
m
s
. We are given the final velocity of Biff (
v
2
=
1
m
s
) and asked to find the final velocity of Bruce.
→
P
f
=
→
p
1
f
+
→
p
2
f
→
P
f
=
m
1
v
1
f
+
m
2
v
2
f
Solve for
v
1
:
v
1
f
=
→
P
f
−
m
2
v
2
f
m
1
Using our known values:
v
1
f
=
720
k
g
m
s
−
(
90
k
g
)
(
1
m
s
)
45
k
g
v
1
f
=
14
m
s
∴
Bruce is knocked backwards at
14
m
s
.
Explanation:
Answer with Explanation:
"Red Blood Cells" <em>(RBCs)</em> contain <em>Hemoglobin</em> that is responsible for carrying oxygen into the body. When people are exposed to higher altitudes, <u>the number RBCs in the body increases</u>. This is because the body has a hard time taking in oxygen due to <u>low atmospheric pressure</u>. It makes it hard for oxygen to pass through the lung membranes. This is called "hypoxia." Such condition deprives the body from oxygen, thus, it creates more red blood cells in order to compensate the condition.
When it comes to people living at sea level,<em> the oxygen can easily pass through the lung membranes</em> due to <u>higher atmospheric pressure.</u> This doesn't require the body to build new RBCs. Therefore, the numbers of RBCs needed by people to thrive is lower than living at higher altitudes.
There are two equal forces of gravity between the Earth and the Moon.
One force pulls the Moon toward the Earth.
The other force pulls the Earth toward the Moon.
If only this gravity suddenly switched off, then the moon would
continue to orbit the Sun, very much as it does now.
If ALL gravity suddenly switched off, then . . .
-- the Moon would stop orbiting the Earth and would sail away, in
a straight line and at the speed it had when gravity disappeared;
-- the Earth would stop orbiting the Sun and would sail away, in
a straight line and at the speed it had when gravity disappeared;
-- all the gases surrounding the Earth ... which we call "air" ... would
start drifting away, and expanding into a giant cloud of gas, and stop
being an atmosphere;
-- the Sun would completely fall apart, expand into a giant cloud of gas,
and stop being a star.
Answer:
a)Taking into consideration Newton’s second law, we know that
Net_Force = mass * acceleration
Since the box is pulled at constant speed, the acceleration is equal to zero.
This means that
Net_Force = 0 N
b) Force of friction
The net force is equal to the sum of all forces,
Net_Force = Force_applied - Friction
We found that Net_Force = 0, which means
Friction = Force_applied = 48 N
c) If the box comes to a stop. And the applied force becomes zero, the friction force becomes also zero.
Friction = 0 N
