Understanding Deceleration: Investigating the Force and Energy Changes on a Ship

[risa]

Homework Statement

1.If the ship has a mass of 2.5 x 10^7 kg calculate the magnitude of the force acting on the ship during the deceleration.

I was trying to work that out using f=ma but that would
Make the force negative , is that possible

2. What is the nature of the force acting on the ship which leads to the deceleratipn and how does it cause the ship to slow down?

Could someone please explain how to do this one please and I also have no idea what "nature of a force" is

3. What is the main energy change as the ship slows down

Is the answer from kinetic to potential?

Homework Equations

The Attempt at a Solution

 

[Chestermiller]

Homework Statement

1.If the ship has a mass of 2.5 x 10^7 kg calculate the magnitude of the force acting on the ship during the deceleration.

I was trying to work that out using f=ma but that would
Make the force negative , is that possible

If the ship is decelerating, the force has to be in the opposite direction from the direction it is moving. So the force is negative.

2. What is the nature of the force acting on the ship which leads to the deceleratipn and how does it cause the ship to slow down?

The problem doesn't tell you what's causing the force. Maybe its a tug boat pulling back on the ship with a rope.

3. What is the main energy change as the ship slows down

Is the answer from kinetic to potential?

What's your understanding of the terms kinetic energy and potential energy?

 

[abcg]

the force would be negative so the answer is 12.5 x 10^4 N
the force acting on the ship slowing it down is friction as the base of the ship is rubbing against the surface of the ocean.
not sure of the energy change though. i know its kinetic to something else...if you get the answer post it please

 

[haruspex]

2. What is the nature of the force acting on the ship which leads to the deceleratipn and how does it cause the ship to slow down?

"Nature" might refer to the source of the force, its characteristics, or both.
Look at the statement at the very top of the attachment. What does it say?
Look at the shape of the graph. What does it tell you about the deceleration? What does that tell you about the force?