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  1. #1 kinematic problems 
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    I have a couple of kinematic problems for class, and I'm a bit confused about how to get the answers for them. Learning about displacement, position, kinematics and Newton's 2nd law. We have a bunch of formulas we're working with and applying where appropriate.

    -Coasting due west on your bicycle at 8.00m/s you encounter a sandy patch of road 7.20m across. When you leave the sandy patch your speed has been reduced to 6.50m/s. Assuming the bicycle slows with constant acceleration, what was the acceleration in the sandy patch?

    initial velocity 8.00m/s, displacement 7.2m, final velocity 6.5m/s, acceleration?

    I think the formula I use is Vf^2= Vi^2+2a(deltaX). And switched around its a=Vi^2+2a(deltaX)(square root of Vf)

    But this gives me 199.8m/s, which I don't think makes sense. Too big. But I'm not sure what I'm doing wrong.


    -Landing with a speed of 115m/s, and traveling due south, a jet comes to rest in 7.00X10^2m. Assuming the jet slows with constant acceleration find the magnitude and direction of its acceleration.
    initial velocity 115m/s, displacement 7.00X10^2m, final velocity 0m/s

    Similar to the first problem, right?


    -A 27.0lb meteorite hit a car leaving a 22.0cm deep dent. If it struck with a speed of 550.0m/s, what was its acceleration, assuming it to be constant?

    I think this is a problem involving Newton's 2nd law (acceleration = sum of forces/mass), but I'm not sure and am also a bit unsure how to figure what the "sum of all forces" are.


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    Quote Originally Posted by arina83 View Post
    I have a couple of kinematic problems for class, and I'm a bit confused about how to get the answers for them. Learning about displacement, position, kinematics and Newton's 2nd law. We have a bunch of formulas we're working with and applying where appropriate.

    -Coasting due west on your bicycle at 8.00m/s you encounter a sandy patch of road 7.20m across. When you leave the sandy patch your speed has been reduced to 6.50m/s. Assuming the bicycle slows with constant acceleration, what was the acceleration in the sandy patch?

    initial velocity 8.00m/s, displacement 7.2m, final velocity 6.5m/s, acceleration?

    I think the formula I use is Vf^2= Vi^2+2a(deltaX). And switched around its a=Vi^2+2a(deltaX)(square root of Vf)

    But this gives me 199.8m/s, which I don't think makes sense. Too big. But I'm not sure what I'm doing wrong.
    Recheck your algebra, the equation you give as solving for 'a' is incorrect. You start out with the right equation, but you rearranged it wrong.


    -Landing with a speed of 115m/s, and traveling due south, a jet comes to rest in 7.00X10^2m. Assuming the jet slows with constant acceleration find the magnitude and direction of its acceleration.
    initial velocity 115m/s, displacement 7.00X10^2m, final velocity 0m/s

    Similar to the first problem, right?
    yes


    -A 27.0lb meteorite hit a car leaving a 22.0cm deep dent. If it struck with a speed of 550.0m/s, what was its acceleration, assuming it to be constant?

    I think this is a problem involving Newton's 2nd law (acceleration = sum of forces/mass), but I'm not sure and am also a bit unsure how to figure what the "sum of all forces" are.
    I think you are to assume that the meteorite comes to a rest at the bottom of the dent, otherwise you have no way of knowing how much velocity the meteorite had after bouncing off the car.


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    The heated mind resents the chill touch & relentless scrutiny of logic"-W.E. Gladstone


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    Geo
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    Read the question carefully. What are your units?..... ms...m...T...p...?

    Check your units and then use the correct formula. Look at each value given, and work it into one of your formulas.
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