Free Fall Under Gravity
Motion under gravity alone, with constant downward acceleration g = 9.8 m/s2, independent of mass.
What is Free Fall Under Gravity?
Motion under gravity alone, with constant downward acceleration g = 9.8 m/s2, independent of mass.
Key formula / rule: g is independent of mass when air resistance is neglected.
Key points
- Apply the equations of motion to vertical free fall with a consistent sign convention.
- Evaluate the claim that heavier bodies fall faster.
Common exam trap
Setting a = 0 at the top of the flight.
Definitions
- Term
Free Fall Under Gravity
- Meaning
Motion under gravity alone, with constant downward acceleration g = 9.8 m/s2, independent of mass.
- Term
Free Fall Under Gravity — explanation
- Meaning
Free fall is the standard test case for constant acceleration. Choosing a sign convention once and keeping it for u, v, a and s is what makes projectile-style problems reliable.
Learning objectives
Apply the equations of motion to vertical free fall with a consistent sign convention.
Evaluate the claim that heavier bodies fall faster.
Formulae
- Key point
g is independent of mass when air resistance is neglected.
- Key point
At the highest point v = 0 but a = g still acts downward.
- Key point
Time up equals time down for a symmetric throw from the same level.
Prerequisites
PHY-U1-KIN-T1-S2-C1
Common mistakes
Setting a = 0 at the top of the flight.
Mixing sign conventions between the upward and downward legs.
Keywords
Under
Gravity
Practice preview
What is the approximate acceleration experienced by an object in free fall near the Earth's surface, neglecting air resistance?…
easy
A feather and a hammer are simultaneously dropped from the same height in a vacuum chamber. Which statement accurately describes their fall?…
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An object is dropped from rest from the top of a building. If it takes 3 seconds to reach the ground, what is the height of the building? (Assume g = 9.8 m/s^2)…
medium