Air Resistance 5
The projectile motion equations from your text (two-dimensional constant-acceleration kinematics equations with ax = 0 and ay = -9.8 m/s2) are valid when an object is subject to the influence of gravity alone. The usual suspect that makes the equations invalid is air resistance (drag). Air resistance is significant in comparison to gravity if any of the following are true:
The projectile motion equations from your text (two-dimensional constant-acceleration kinematics equations with ax = 0 and ay = -9.8 m/s2) are valid when an object is subject to the influence of gravity alone. The usual suspect that makes the equations invalid is air resistance (drag). Air resistance is significant in comparison to gravity if any of the following are true:
1) Small object (ex: dust)
1) Small object (ex: dust)
2) Low density object (ex: balloon)
2) Low density object (ex: balloon)
3) Fast object (ex: bullet)
3) Fast object (ex: bullet)
4) Broad cross sectional area object (ex: parachute).
4) Broad cross sectional area object (ex: parachute).
A person tightly wads up a sheet of paper and then throws it a short distance.
A person tightly wads up a sheet of paper and then throws it a short distance.
A) Air resistance is not significant. The projectile motion equations are valid.
A) Air resistance is not significant. The projectile motion equations are valid.
B) Air resistance is significant. The projectile motion equations are not valid.
B) Air resistance is significant. The projectile motion equations are not valid.