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d1i1m1o1n [39]
2 years ago
15

Tim sets up an experiment with 3 groups of runners. Group 1 smokes 1 pack per day. Group 2 smokes 2 packs per day. Group 3 smoke

s 3 packs per day. Tim does a study to determine whether or not cigarette smoking decreases speed in track runners. After 1 month, Tim measures the average 40 yard dash time for each group and finds that group 3 was the slowest, 2 was in the middle, and 1 was the fastest. He concludes that cigarette smoking decreases speed, but this is not necessarily correct. What was wrong with his experiment? A) Tim measured more than one independent variable. B) Tim did not have a dependent variable. C) Tim did not use a control group. D) Tim did not have a hypothesis.
Physics
1 answer:
Anna007 [38]2 years ago
5 0

Answer:

Tim did not use a control group

Explanation:

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a golf ball is hit with a velocity of 30.0 m/s at an angle of 25 degrees about the horizontal. how long is the ball in the air a
Pie
Ok so use trigonometry to work out the vertical component of velocity.

sin(25) =opp/hyp
rearrange to:
30*sin(25) which equals 12.67ms^-1

now use SUVAT to get the time of flight from the vertical component,

V=U+at

Where V is velocity, U is the initial velocity, a is acceleration due to gravity or g. and t is the time.

rearranges to t= (V+u)/a

plug in some numbers and do some maths and we get 2.583s

this is the total air time of the golf ball.

now we can use Pythagoras to get the horizontal component of velocity.

30^2-12.67^2= 739.29
sqrt739.29 = 27.19ms^-1

and finally speed = distance/time

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The ball makes it to the green, and the air time is 2.58s 
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Explanation:

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Answer:

hey there

( i )we have to Choose good nutrition. A healthy diet is one of the best weapons you have to fight cardiovascular disease. and should be physically active and stop smoking if you do these are some

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Explanation:

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