All Solutions
Page 89: Practice Problems
textit{color{#c34632} $ See $ $ Answer $}
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textit{color{#c34632} $See$ $ Answer$ }
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textit{color{#c34632} $ See $ $ Answer $}
$$
textit{color{#c34632} $ See $ $ Explanation $}
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textit{color{#c34632} $ See $ $ Answer $}
$$
$$
begin{align*}
F_1&=225 mathrm{N} \
F_2&=165 mathrm{N}
end{align*}
$$
Unknown:
$$
begin{align*}
F_{net}&=?
end{align*}
$$
$$
begin{align*}
F_{net}&=F_1+F_2 \
&=225 mathrm{N}+165 mathrm{N} \
&=390 mathrm{N}
end{align*}
$$
begin{align*}
F_{net}&=390 mathrm{N} tag{in the direction of two forces}
end{align*}
$$
From the question, we know that, $F_{1}$ is 225 N and $F_{2}$ is 165 N
If both the forces are in same direction, they will be added but if their direction is opposite, they will be substracted.
In this question, both forces are in same direction.
So therefore, the formula will be:
$textcolor{#c34632}{F_{net} = F_{1} + F_{2}}$
1) Using the formula stated in cell 2.
$F_{net}$ =$F_{1}$ + $F_{2}$
2) Substituting the values in the formula :
$F_{net}$ = 225 + 165
$$
boxed{ F_{net} = 390 text{ N }}
$$
boxed{ F_{net} = 390 text{ N }}
$$
$$
begin{align*}
F_1&=225 mathrm{N} \
F_2&=-165 mathrm{N}
end{align*}
$$
Signs indicate direction only.
Unkonown:
$$
begin{align*}
F_{net}&=?
end{align*}
$$
When two forces act in opposite directions, we also get the net force by summing but now we have to pay attention to the sign of the forces.
$$
begin{align*}
F_{net}&=F_1+F_2 \
&=225 mathrm{N}-165 mathrm{N} \
&=60 mathrm{N}
end{align*}
$$
Note that the net force is a positive sign which means it is looking in the direction of a larger force.
begin{align*}
F_{net}&=60 mathrm{N} tag{in the direction of larger force}
end{align*}
$$
$$
begin{align*}
F_{Alutia}&=35 mathrm{N} \
F_{Seward}&=42 mathrm{N} \
F_{Kodiak}&=-53 mathrm{N}
end{align*}
$$
For the positive direction, we chose the east direction.
Unkown:
$$
begin{align*}
F_{net}&=?
end{align*}
$$
To get net force, we add upp forces of individual dogs.
$$
begin{align*}
F_{net}&=F_{Alutia}+F_{Seward}+F_{Kodiak} \
&=35 mathrm{N}+42 mathrm{N}-53 mathrm{N} \
&=24 mathrm{N}
end{align*}
$$
The sign of the total force is positive, ie in the eastern direction.
