One Dimentional Relative Motion

[shizaep]

Homework Statement

An ocean liner approaches a peer at 20km/h. When the ocean liner is 10 km away, the captain sends a speedboat to the pier to pick up the harbour pilot, who will help dock the ocean liner. The speedboat takes 12 min to get to the pier.
a) How long would the speedboat take to return to the ocean liner if it maintains the same speed?
b)Find the displacement of the speedboat during the round trip and the distance covered by the speedboat during the round trip.

Homework Equations

x_ab(t) = 1/2 a_abt^2 + v_oab + x_oab

The Attempt at a Solution

a) (0) = (0) + (8.33)t + (0)

??

 

[MostlyHarmless]

That's not much of an attempt. Do you have any specific questions? What are you getting hung up on?

 

[shizaep]

Since relative acceleration is zero, there would only be one solution for t, at 0?
Makes no sense so I definitely did not construct the equation correctly

 

[MostlyHarmless]

I don't think your looking at this right.

Acceleration is constant, so just take that out of your equation.

$x(t)=x_{b0}+v_b(t)$, where$v_b$ is the velocity of the ocean liner, if it takes the speedboat 12 minutes to get to the shore how far as the Ocean liner traveled in that time? What is the speedboats velocity? $v_s={\frac{x}{t}}$, where $v_s$ is the velocity of the speedboat.

Now that should get you started, keep in mind that the Ocean Liner is constantly moving.

 

[Nickie]

b) The displacement of the speedboat during the round trip would be 20 km (10 km away from the ocean liner to the pier, and 10 km back to the ocean liner) in the positive direction. The distance covered by the speedboat during the round trip would be 20 km, as it travels 10 km to the pier and 10 km back to the ocean liner.