Question

question 9
the fall of bodies in the air
without any air, all objects fall with the same ______. when air is present, a friction - like force called the ____ acts on the object. the force depends on the ____ and ____ of the object, the ____ of the air, and the ____ of motion. when this force equal to the force of gravity the net force on the object is ____, and the object has reached its ______ velocity.
word bank:
shape terminal density zero acceleration speed drag force size
blank 1:
blank 2:
blank 3:
blank 4:
blank 5:
blank 6:
blank 7:
blank 8:

Explanation:

• In a vacuum (no air), all objects fall with the same acceleration due to gravity (\(g = 9.8\ m/s^{2}\) near the Earth's surface).
• When air is present, the drag force (a friction - like force) acts on the object.
• The drag force \(F_d\) is given by formulas like \(F_d=\frac{1}{2}

ho v^{2}C_dA\) (where \(
ho\) is air density, \(v\) is speed, \(C_d\) is the drag coefficient related to shape, and \(A\) is the cross - sectional area related to size). So it depends on the size and shape of the object, the density of the air, and the speed of motion.

• According to Newton's second law \(F_{net}=ma\). When \(F_d = F_g\) (force of gravity), \(F_{net}=F_g - F_d=0\).
• When \(F_{net} = 0\), from \(F_{net}=ma\), \(a = 0\). The object's speed no longer changes, and it has reached its terminal velocity.

Answer:

Blank 1: acceleration
Blank 2: drag force
Blank 3: size
Blank 4: shape
Blank 5: density
Blank 6: speed
Blank 7: zero
Blank 8: terminal