Answer:
B
Explanation:
Displacement, velocity, and acceleration are vectors: they have magnitude and direction.
The convention is that "down" is negative and "up" is positive.
Thus, if an object is higher than when it started, its displacement is positive. If it is lower, the displacement is negative.
If it is still going "up", its velocity is positive. If it is falling, its velocity is negative.
1. Displacement
The formula for vertical displacement is
Δy = v₀t - ½gt²
If v₀ = 30 m/s, t = 2 s, and g = 9.8 m·s⁻², then
2. Velocity
The formula for vertical velocity is
v = v₀ - gt
If v₀ = 30 m/s, t = 2 s, and g = 9.8 m·s⁻², then
3. Acceleration
The vertical acceleration is always -g = -9.8 m·s⁻².
The direction of the acceleration is down.
The only option with the sequence "up, up, down" is B.