Answer
a) See the detailed answer below.
b) $15.1\;\rm m/s^2$
Work Step by Step
a)
A plane jet toy that weighs 9.8 N is speeding up toward the east at a constant rate. The drag force exerted on it is assumed to be constant and is about half its weight.
Its motor is applying a thrust force of 20 N.
Find its acceleration.
b)
$$\sum F_x=20-4.9=ma_x\tag 1$$
We know that the mass is given by
$$F_G=mg=9.8$$
Thus,
$$m=\dfrac{9.8}{g}=1\;\rm kg$$
Plugging into (1);
$$ 20-4.9=115.1\cdot a_x $$
Thus,
$$a_x=\color{red}{\bf 15.1}\;\rm m/s^2$$
