A gannet flying above the ocean spots a school of fish near the surface. It wheels about and dives, taking a straight trajectory down into the water. Success! A fish!

Attached is a velocity-time graph of the gannet's dive, assuming that it starts with zero downward velocity.

A velocity time graph of a gannet diving into the water for fish. Time is on the x-axis. Velocity is on the y-axis. When the gannet moves up, this is considered positive acceleration and is therefore above the x-axis. When the drone moves down this is considered negative velocity so this appears below the x-axis. All sections of the slope are below the x-axis. At point A on the graph the gannett has zero velocity. The slope between point A and B is a gentle downward slope. The slope between point B and B is a steep upward slope. At point C the velocity of the gannet is 0.

Explain the graph in terms of what is happening to the gannet at each stage of the dive. Answer the following:

1. When does the gannet start its dive?

2. When does it enter the water?

3. When is the gannet stopped, at the bottom of its dive?

4. When is the gannet accelerating, and how – that is, is it slowing down or speeding up?

5. Ignoring whether it is positive or negative, which has greater magnitude – the gannet's acceleration before it enters the water, or after? How do you know?