(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A water skier is going to glide up a 2.0m frictionless ramp then sail over a 5.0m wide tank filled with sharks, she'll drop the tow rope at the base of the ramp. What minimum speed must she have as she reaches the ramp in order for her to clear the sharks.

2. Relevant equations

1/2mv^2=mgh

Vf^2=Vi^2 +2ax

t=sqrt of 2(height)/g

3. The attempt at a solution

figured out time to fall 2 meters = .63 seconds. So she'll need to cross the 5.0m wide tank in this amount of time. 5/.63 = 7.82 m/s this is the speed needed as she leaves the top of the ramp.

1/2mv^2=mgh solved for v

v=sqrt of 2gh

this is the speed needed to make it from the the bottom of the ramp to the top.

=6.26 m/s

add these two speed together and it should be velocity at bottom of ramp 6.26+7.82 =14.1 m/s

or so I thought. Book gives answer as 10 m/s.

so which calculation is wrong? 10-7.82 =2.18 m/s this isn't enough to make it up the ramp.

10-6.26 = 3.74 this isn't enough speed to make it over the sharks.

All I can think is that maybe I am calculating the speed to get up the ramp incorrectly.

Any help?

Thanks.

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