- #1

chops369

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**Homework Statement**

Ok, I have a couple problems that I'm having trouble with. Bear with me, my physics teacher can be a little creative...lol.

1. I am an expert swan diver. If I am jumping off a 3m diving board, what is the velocity with which I strike the water? If the water brings me to rest in 0.3 seconds, what is the force the water applies to me?

2. Driving along in your 850 N Mini Cooper you pass by a hemp clothing yard sale and slam on your brakes. If you were traveling 20 m/s and your brakes apply a force of 8000 N in the opposite direction, how long does it take you to stop? How far do you skid?

3. Super Mario, who weighs 5 kg, is standing on a platform, which weighs 25 kg. Seeing Bowser in the distance he jumps off the platform with a speed of 3 m/s to the right. What is the final velocity of the platform?

**Relevant equations**

Vi = √2ghi

F∆t = -mVi/∆t

F∆t = mVf - mVi

m

_{1}V

_{1},

_{i}+ m

_{2}V

_{2},

_{i}= m

_{1}V

_{1},

_{f}+ m

_{2}V

_{2},

_{f}

I'm not sure if there are any others that I need, but I have a feeling that I'm missing something.

**The attempt at a solution**

For the first problem, I used Vi = √2ghi and found the man to be going 7.7 m/s. Then I tried to use the equation F∆t = -mVi/∆t, but I don't have the mass. Is there another equation to use or did my teacher just forget to include mass? (he does that a lot)

For the second one I think it has something to do with the impulse momentum theorem, but how would I find the skid distance with that?

For the third one, I'm pretty sure I need to use m

_{1}V

_{1},

_{i}+ m

_{2}V

_{2},

_{i}= m

_{1}V

_{1},

_{f}+ m

_{2}V

_{2},

_{f}. But I don't really know where to start.

EDIT: I just tried to solve number 3 and I got -0.6 m/s. Is this correct? I'm still not too sure about the other problems though.

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