Question

Air drag is like a friction force in that it acts to resist motion of an object through the air. Consider an object falling through the air and select all the correct statements that could describe the motion of the object while it is falling.

1.Since there are always forces acting on the object, it is constantly accelerating (not = 0)

2.The sum of forces on the object could be zero despite falling

3.The speed of the falling object will tend to go down with time

4.Given time, the downward acceleration of the object will approach zero

5.An object can fall at constant speed

6.Newton's second law does not apply since air drag is not a constant force

Answer 1

although the air drug acts on the body ,but its velocity increases in downward direction and air drag is also increases but acceleration is always is constant.This motion can be described or solve by the newtons 2 nd laws of motion, i.e all forces(body s acceleration in downward direction and dragforce in opposite direction all ) acts upon the body is equal to zero.  the body s speed increses to conserve the energy , as in downward potential energy decrease so kinetic energy as well as velocity increases to conserve the energy. so option 1,2 is correct.

if the body falls from too much height then it reaches to the terminal velocity then its speed will be constant and hence acceleration is zero.