Question

An object of mass 8.0kg is falling vertically through the air. The drag force acting on the
object is 60N. What is the best estimate of the acceleration of the object?

Answer 1

Answer:

2.5m/s^2

Explanation:

The 60 N drag force is opposing the mass of the object.

This creates a total force of 20 N

Then, F=ma

20=8 x a

a=2.5m/s^2

Easy to take F as 60 N only which would give 7.5m/s^2 instead. But the drag force is opposing the mass.

Answer 2

Given:

An object of mass 8.0kg is falling vertically through the air. The drag force acting on the  object is 60N.

To find:

Net acceleration of object?

Solution:

• Mass of 8 kg is experiencing drag of 60 N.
• Let's assume that net acceleration of object is 'a':
• Also, we know that : force acts opposite to the direction of movement of the object, i.e. acts opposite to 'g'.

$a = \dfrac{ F_{net} }{m}$

$\implies a = \dfrac{mg - drag }{m}$

$\implies a = \dfrac{(8 \times 10) - 60 }{8}$

$\implies a = \dfrac{80 - 60 }{8}$

$\implies a = \dfrac{20 }{8}$

$\implies a = 2.5 \: m {s}^{ - 2}$

So, net acceleration of object is 2.5 m/s².