1-d kinematics food fight in space

[tri5]

Homework Statement

Having aced your Physics 2111 class, you get a sweet summer-job working in the International Space Station. Your room-mate, Cosmonaut Valdimir tosses a banana at you at a speed of 14.0 m/s. At exactly the same instant, you fling a scoop of ice cream at Valdimir along exactly the same path. The collision between banana and ice cream produces a banana split 6.0 m from your location 1.3 s after the banana and ice cream were launched.

1) How fast did you toss the ice cream? 4.6153 m/s

2) How far were you from Valdimir when you tossed the ice cream?

Homework Equations

v = v_0 + a t
x = x_0 + v_0 t + (1/2) a t^2
v^2 = v_0^2 + 2 a \Delta x

The Attempt at a Solution

My attempt at the solution is in the pdf file.
I am having trouble with question 2. I calculated the acceleration of the banana by dividing the initial velocity by the time, then plug it in x = x_0 + v_0 t + (1/2) a t^2. With t = 1.3s, v_0 = 14 m/s, and a = -10.7692 m/s^2.
My delta x = 9.1
I then added the 6m + 9.1m = 15.1m, but the automated homework system says the the answer is incorrect.

 

[TSny]

Hello tri5. Welcome to PF!

The speed of 14.0 m/s for the banana is the speed it left your room-mate's hand. Once it leaves the hand, does it have any acceleration?

 

[tri5]

No the banana does not have any acceleration. I ended up multiplying the velocity of the banana by the elapsed time, which gave me the distance it traveled. Then adding that answer to 6m gave me the correct answer. Thanks for your help!

 

[TSny]

Good work!

 

[Nickie]

Can you please help me find my error?


Hello! It looks like you are on the right track with your calculations for the second question. However, I believe the error may be in your units. In your calculations, you used seconds for the time and meters per second for the initial velocity, which would result in meters for the acceleration. However, in the equations you used, the units should be in meters per second squared for acceleration. Therefore, your acceleration should be -10.7692 m/s^2, not just -10.7692 m/s. When you use the correct units, your delta x should be 15.1 m, which matches the answer given by the automated homework system. Keep up the good work!