Aroller coaster starts from rest at its highest point and then descends on its (frictionless) track. its speed is 40 m/s when it reaches ground level. part a what was its speed when its height was half that of its starting point? what was its speed when its height was half that of its starting point? 33 m/s 14 m/s 20 m/s 28 m/s

Given that,

Initial velocity , Vi = 0

Final velocity , Vf = 40 m/s

Acceleration due to gravity , a = 9.81 m/s²

Distance can be calculated as,

2as = Vf² - Vi²

2 * 9.81 *s = 40² - 0²

s = 81.55 m

For half height, that is, s = 40.77m

Vf= ??

2as = Vf² - Vi²

2 * 9.81 * 40.77 = Vf² - 0²

Vf² = 800

Vf = 28.28 m/s

Therefore, speed of roller coaster when height is half of its starting point will be 28 m/s.  

a long strand of spaghetti is folded once. if this is cut 20 times, how many pieces of spaghetti will there be? a long strand of spaghetti is folded once. if this is cut 20 times, how many pieces of spaghetti will there be? a long strand of spaghetti is folded once. if this is cut 20 times, how many pieces of spaghetti will there be? a long strand of spaghetti is folded once. if this is cut 20 times, how many pieces of spaghetti will there be? a long strand of spaghetti is folded once. if this is cut 20 times, how many pieces of spaghetti will there be?

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they are non-matter

explanation:

they are non-matter. basically, any type of energy or any abstract concept is an example of something that does not matter. other examples include dreams, magnetism, radio, and hate