physics unit 1 - andrews universityrwright/physics... · the models, theories, and laws we devise...

Physics Unit 1

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The models, theories, and laws we devise sometimes imply the existence of objects or phenomena as yet unobserved.However, if experiment does not verify our predictions, then the theory or law is wrong, no matter how elegant or convenient it is.

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Meter based on distance light travels in a vacuum in 1/299,792,458 of a secondSecond based on time it takes for 9,192,631,770 vibrations of Cesium atomsMass based on mass of a platinum-iridium cylinder kept with the old meter standard at the International Bureau of Weights and Measures near Paris

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Δ𝑥 = 𝑥 − 𝑥0Δ𝑥 = 7 − −5 = 12

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(a) Find the slopes by drawing tangent lines, sketch graph based on these values(b) d(c) c,e,g,l(d) a,b,f

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(a) Speeding up(b) Slowing(c) Slowing(d) Speeding up

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a) 𝑣2 = 𝑣02 + 2𝑎 𝑥 − 𝑥0

26𝑐𝑚

𝑠

2

= 0𝑚

𝑠

2

+ 2𝑎 2 𝑐𝑚

676𝑐𝑚2

𝑠2= 4𝑎 𝑐𝑚

𝑎 = 169𝑐𝑚

𝑠2

b) 𝑥 = 𝑥0 + 𝑣𝑡; 𝑣 =𝑣+𝑣0

2

𝑣 =0𝑐𝑚𝑠 + 26

𝑐𝑚𝑠

2= 13

𝑐𝑚

𝑠𝑥 = 𝑣𝑡 + 𝑥0

2 𝑐𝑚 = 13𝑐𝑚

𝑠𝑡

𝑡 = 0.15 𝑠

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When solving and taking square root, then use ± sign. Took negative here because it was going down.

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It’s going down.

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Note at highest point, vy = 0

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Note at highest point, vy = 0

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X-velocity doesn’t change since no acceleration in x

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Hit at the same time since they fall down the same distance and have the same initial y-velocity.

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Watch MythBusters bullet drop video

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